Note - the "She thinks" part may or may not be accurate...I'm trying to construct it based off all the things I've heard girls tell me when it comes to these things. But I'm a guy, so genetically I can and never will understand women. Plus most of the girls I know are pretty silly, so some of them may be off. My apologies if I'm way off on any.

Common Mistakes Girls Make in Pursuit of Guys

Okay, so we all know that guys can be pretty boneheaded when it comes to dating. Do or say the wrong thing, and he goes straight into the hells of the Friend Zone™, never to return. But girls can be guilty of the same mistakes. Little behaviours that can make a guy go from interest to frustration in no time flat. So, for the ladies, a list of common things that makes guys just not want to date you.

Calendar Syndrome - She leads a busy life. That's understandable. School, work, friends, committments, et al. As a result, scheduling a date with her is quite difficult. The guy always has to work around something, and sometimes she may have to even cut it short in order to fulfill some other committment.
She thinks: She may actually really just be incredibly busy. Plus, some girls will try to appear busier than they are just to make it seem like they are popular - a social butterfly.
He thinks: Not worth the effort. Why bother if he'll hardly get to see her? Find someone else who actually has the time for him.
What she should do: Surely she can free up a few hours a week in order to see him. She should be able to get together with him, at the very least, once a week. If not...then maybe she just isn't at a place in her life where a boyfriend/romantic interest fits in.

Failure to Reciprocate - The guy makes initial contact, calling and setting up the first few dates. But the girl always waits for him to call, him to make the next date.
She thinks: She doesn't want to appear too forward and desperate. If he approves of her, he'll call.
He thinks: If she's not putting in the effort, why should he?
What she should do: CALL HIM. Call just to say hi. Or set up a date of her own. This lets the guy know that you are interested, and that he won't be doing all the work. Guys absolutely hate it if she sits around and does nothing to help foster the relationship. If that happens, he'll lose interest and find someone who is willing to reciprocate.

Failure to Reciprocate 2 - Hesistation and Resistance - The guy calls her and tries to set up a date, but its nothing she wants to do. Already seen the movie. Isn't hungry. Her favorite TV show comes on tonight. Waiting for a call from a friend. Etc.
She thinks: She honestly just don't want to see the movie again, is not hungry, really wants to see the TV show, etc.
He thinks: All of the above take precedence over spending time with him.
What she should do: The point is not what you do - the point is spending time with him. If she's already seen the movie he suggests, recommend another. If she isn't hungry, go and order a salad. Or suggest a dessert. Tape the damned TV show. Call the friend back later. The activity that brings the two together is in many ways irrevalent - he just wants to see her. If she can't at least do that, he will assume disinterest and move on.

Free Counseling - The "Issues" - She's starting to get comfortable with him. So now its time to "open up". Start sharing her feelings. Come to him with problems/concerns in her life.
She thinks: She's showing how much she trusts him, and the two are becoming closer.
He thinks: He's her intellectual whore - her free counselor. And that's a brazen sign of the Friend Zone™. Get out now while the gettin's good.
What she should do: Save the Montel Jordan until the relationship is established. Many guys don't like to hear that shit even during the relationship, they sure as hell don't want to hear it in the dating stage. The point of dating is to get to know each other better, and have a lot of fun. Bringing issues into the mix is NOT fun, and subsequently, NOT attractive. Besides, how will telling him about her high school drama with friends make her more desireable?

Forced Conversation - While out, he isn't saying much. She feels awkward, and tries to force conversation. Start digging into his life, reveal aspects of her own, whatever she can do to fill the silence with noise.
She thinks: If you two were really getting along, you would be talking non-stop. You have to be constantly relating to each other.
He thinks: Shut the hell up. Please.
What she should do: Guys don't always need to be talking. If he's not talking, that doesn't mean he doesn't like her, doesn't approve of her, doesn't trust her. Maybe he's just tired. Maybe he just honestly has nothing to say. Awkward silence always sucks, but if we can sit there in comfortable silence, that's golden. If the conversation is coming, fine. If not, don't force it. That's not going to help her any.

Lack of Self-Confidence - She's always self-depreciating in some way. Saying things like "I look terrible today" or "Am I as pretty as her?" He takes her to a fancy restaurant and she doesn't want to order because its too expensive. Et al.
She thinks: She does not want to appear egotistical and conceited.
He thinks: If she doesn't even like herself, why should I?
What she should do: For guys, always having to pick the girl up gets really old really fast. Guys are attracted to looks, yes, but in the long run, personality is what really matters. If he likes her for who she is, he will be into her regardless of what she looks like. She should be comfortable with herself. And definitely don't go fishing for compliments. The guy will give them when appropriate.

Breakdown of Communication/Indirectness - He can never get her to admit that they're going out of a date. She will not ask him directly for things, but hint around, elude to it. She tells her friends more about what she thinks of the guy/the dates than she tells him.
She thinks: She doesn't want to expose herself and her feelings to the guy before she knows where he stands. She doesn't want to be too forward and be percieved as pushy.
He thinks: If he wanted to play games, he'd go to the arcade.
What she should do: Guys HATE indirectness. TELL HIM what you are feeling. Do not be afraid to say "we are dating." We want answers, damnit. Communicate to him, not friends. And if you want something, ask. Do not expect us to figure it out, because no man has ever been able to truly break down the thought processes of women, and he is no exception. Guys will appreciate your ability to actually talk to him.

"Bullpen Syndrome" aka The Surprise Boyfriend - Sometime during dating, the guy will learn that the girl already has a boyfriend. Imagine that.
She thinks: (as far as I can tell) Oftentimes, when a girl becomes tired of her current relationship, she'll start dating other guys...but not break things off with the current bf. Just in case things don't work out with the guy she's dating, she'll have the existing bf to fall back on. Like warming a pitcher up in the bullpen while the starter's still on the mound.
He thinks: A. What the fuck. B. Don't date me while you have a bf. That's not cool. C. Even if we did hook up, whose to say she won't do that to me at some point in the future? D. Is she that afraid of being alone? Those are some serious dependency issues. And NO ONE wants that.
What she should do: If she's tired of her current guy, DUMP HIM. It's best for everyone. If she meets someone new and wants to try it, DUMP THE CURRENT and try it. Yeah, she's taking a risk. But hey, no one said this shit was easy. The truth always comes out, and she'll end up with no one.

Indecisiveness aka "I Don't Know" Syndrome - The guy calls to make plans. Being polite, he asks the girl what she wants to do, where she wants to go eat, etc. The girl answers "I don't know." and leaves the choice to the guy.
She thinks: She honestly doesn't know. Or maybe she is afraid of picking something he won't like. Or she doesn't want to seem too forceful.
He thinks: !#@%%#@@!%!@#%!!
What she should do: This. Really. Pisses. Guys. Off. It wouldn't be so bad if this was the response every now and then, but this is the response 99.9975% of the time. Sadly, most guys have trained themselves to accept that this is the Universal Female Response, so he will be prepared. However, as a guy myself, I'm listing this as a mistake because if you, as a girl, can actually decide on what you want to do/where you want to eat/etc, this will score you major points in the guy's book. Just suggest something, and if he doesn't want to do it, he'll let you know. It all comes back to communication.

Unequal Ground - She expects certain things from him, but she is not willing to do the same. She expects him to cancel plans with his friends if she wants to go out, but cancelling with her friends is out of the question. She expects him to buy her gifts/flowers randomly, but will never buy anything for him. She always expects him to pay. And so on.
She thinks: The guy is the suitor, and as such, he must prove his worth to her.
He thinks: To hell with that. He'll find a girl who isn't quite as high maintainance.
What she should do: Get with the times. Women have fought for equality in all aspects, and relationships are no exception. If she expects the relationship to be on her terms, well, she's not going to have very many. The few guys she'll find that will agree to this will be the spineless, housebroken ones who are generally bad relationship fodder to begin with. Only ask no more than what you are willing to do, and even then try not to be unreasonable. Expecting him to cancel plans with friends is a bit too much.

Too Much Too Fast - The Dreaded "L" Word - Maybe she's been ready for a relationship for quite some time now. So now that she's dating a guy, she's getting a bit ahead of herself. She's already expecting him to play the role of the BF, doing some of the things mentioned above like expecting certain things from him, and the whole "open up and sharing" bit. Maybe she even uses that frightening word...l...l....lo...love. She calls and/or expects to see him everyday.
She thinks: She's found a winner. Why wait? Lets jump into the committment and enjoy it all the more sooner.
He thinks: ....Whoa. You don't even know me that well and you're already naming our kids?!
What she should do: It takes genuine time to get to know a person. Not two weeks, not two months, but a significant amount of time and effort. If she invests too much too soon, that's way scary. Plus, it shows dependency issues that are far reaching. Don't let your feelings get ahead of you. Don't overanalyize and overthink things - take things as they come, and let everything develop naturally.

Just one of the Guys - She's a rare breed, who enjoys sports and even video games. As a result, she tends to have a lot more guy friends than girl friends. And that's fine. Guys actually like a girl who can watch sports with them (just as long as they know not to ruin it with off-topic talking). But she seems to always talk about her guy friends, especially one in particular.
She thinks: She's showing him how well she can relate to guys, so she'd be a good match for him.
He thinks: Maybe she likes one of those guy friends, not him.
What she should do: Even for a guy who is relatively secure with himself, hearing her rave about different guys too often will make him nervous, espeically if its one in particular. Lay off too much of the guy friend talk. Along the same vein, NEVER talk about any guys you find cute/attractive/dateable. He'll think that if you are discussing with him, then obviously you don't think of him as anything more than a friend. A possible exception would be celebrities, but even then its better to just not talk about it at all.

Lack of Physical Affection - Maybe the guy tries to put his arm around her, rub her shoulders or whatever, but she pulls away, or seems uncomfortable. She never initiates any physical contact whatsoever.
She thinks: She could be really shy and not comfortable with physicality. Or maybe she doesn't want to seem too touchy feely, and send the wrong signals.
He thinks: If she doesn't want to get even a little physical, then obviously we're just friends.
What she should do: You can have a great time on dates...but then again, so can friends. Something has to be done to establish that this is towards a romantic relationship. If this is going to be a relationship, physicality is going to come into play at some point - otherwise, its just a friendship. He doesn't want to jump down her pants or anything like that. But just show him that you are physically attracted to him/receptive to him. Return the arm around the shoulder. Play with his arm or leg. Kiss him if things are going well. There has to be something to distinguish that this is more than just friends. If she isn't quite comfortable with physicality, then she'll need to convey her interest in romance in other ways. Here's one I highly recommend - actually tell him that you're interested in a relationship! Radical, maybe, but something must be done. If this scares off a guy/makes him lose interest, that's not a guy you'd want to be dating anyway.

Three (or more) is a Crowd - He or she suggests a date, which is agreed on. She then invites friends.
She thinks: Having her friends there might make the date more fun. Plus, they can meet the guy, and give her advice/feedback on him.
He thinks: This is not a date. You do not invite friends on dates.
What she should do: Leave the pals at home. Especially in the initial stages. If she really wants them to meet him, she can arrange for him to see them briefly...maybe they're over when he picks her up. But leave them behind. For guys, dates are an intimate activity, and that is obliterated when the friends come tagging along. It just sends a clear signal that she is interested in him on the friend level only.

Three (or more) is a Crowd 2 - Double Agent Girl - In a situation where he sees her when she's around her friends (if she invited them on a date, hopefully not, or if he runs into her randomly somewhere), she acts differently around him. Is not as friendly/affectionate. Seems to barely know him, barely care. Just acts different in general.
She thinks: Maybe she doesn't want her friends to see that side of her. Maybe she hasn't told them about him, and doesn't want them to catch on.
He thinks: He doesn't know what to think. Seriously.
What she should do: Avoid this situation if possible. This is another reason why I hate friends on dates, because then she has to decide how much attention she is going to pay to her friends Vs the guy. That's a delicate matter, which is best handled by avoiding it all together. In cases of random meeting, don't be cold to him. Personally, I say get him out of there. Say your hellos and what not, then tell him you will call him later. And actually do so! Keep things separate at this point.

Cell Phone Deference - This gets a category of its own because, IMHO, it's pretty big. She's out on a date with the guy, and then her cell phone rings. She answers it...and PROCEEDS TO TAKE THE CALL.
She thinks: If any of you ladies can actually break down what the hell you're thinking here, I'd love to hear it.
He thinks: Clearly, he's not important enough to hold her interest. Not to mention that he made the effort to get together and bring her out, while the joker who called on the cell gets priority.
What she should do: Turn the damn cell phone off. Completely off. If you leave it on, don't answer it. If you're afraid of emergencies and do answer it, unless it is an emergency, tell the other person you'll call back later AND HANG UP. Even a five minute convo on the cell can really hurt her standing with the guy. Nobody likes playing second banana to a cell.

Bad Hygiene - (seems a little obvious, doesn't it?) She goes out on a date...and hasn't had the time to properly prepare. Maybe she's been out all day, so she smells a little. Bad breath. Hasn't shaved. Maybe lays on the perfume a little too thick. I would even put too much makeup in this category.
She thinks: There's this odd phenomeon on the female 1 hr 15 min shower that I just can't comprehend. So, maybe she didn't have the "time" to prepare. Or maybe she just doesn't realize her funk.
He thinks: A. That's nasty. B. Obviously, he's not important enough to warrant a shower/a few breath mints.
What she should do: Clean up. Please. If he wants to go out at 6, and you get off work at 5, ask him if you can go at 7 to give yourself more time to prepare. It may sound shallow, but if she comes bringing the funk, that's not attractive at all. And it shows the guy he isn't important enough for her to get all dressed up/cleaned up for. Similarly, don't make him wait while you're still prepping. Manage your time wisely, and be ready to go when he gets there.

I think the bottom line here is reciprocation and openness. Don't sit back and make him come to you. Show him you are every bit as interested as he is, maybe more so. If you're willing to meet him halfway - call him sometimes, make the dates, and just be willing and receptive to his offers...this will go a long way.