Don't:
Pretend to be something you're not. I'm sure that you've heard the phrase "It's better to be hated for something you are than to be loved for something you're not". There's a lot of wisdom in that saying, but so many people simply ignore the truth because it's inconvenient. It just doesn't work that way. I see so many girls playing dumb to get attention or to make a guy feel superior. They change who they are to get a guy or to keep a boyfriend. Is that really love, or is it just an overwhelming desire to fit in and be wanted? Do you see guys putting aside their beliefs, desires, values, and interests just to get/keep a girlfriend. No. So why should you? Besides, if you're pretending, they don't "love" you, they love who you're pretending to be. So, in the end, what's the point? Five years from now, will it matter that you dated a cute guy in seventh grade? No, no it won't. In the long run, it doesn't matter, so why change yourself for something that won't last? Why make yourself miserable? There are only two possible outcomes of dating anyway: marriage or breaking-up. Don't date someone you can't see yourself marrying.
Dress scantily. Yeah, I know I sound like your mother or your Great Aunt Martha, but think about it. If your shorts could be mistaken for underwear and your top barely covers your bra, what do you think guys are seeing when they look at you? They certainly aren't noticing your beautiful smile, charming personality, or bright eyes. They don't see YOU, they see your body. You can't REALLY see the inner beauty when the outer kind is covering it up. I'm not saying that being pretty or wearing that cute top is wrong - because physical attraction is definitely a factor - but do you want that to be all they see? Besides, what kind of guy are you going to attract when you dress like that? Most likely not one that would sign the boyfriend manual, much less respect you. Just think about it. Do you want your guy to love your body or your soul?
Think that you can change a guy. This is one of the most common mistakes that women make. They think that they can change guys. Newsflash: people don't change, and if they do, it's very, very rare. If he's lazy/arrogant/abusive now, then he probably always will be. He has to WANT to change; you can't make him. Please don't fool yourself into thinking you can.
Bad-mouth others. I can't think of a more unattractive quality. No matter how physically pretty you are, this instantly taints your appearance. Besides, those who hear you bad-mouthing others are likely to assume that you would do the same to them. No guy wants you making fun of him behind his back, and he probably doesn't want to hear you gripe about that slut in English either. Of course, if someone asks you, then it's perfectly fine to tell them the cold, hard facts, but anything past that just isn't a good idea.
Do:
Smile. It's an instant beauty boost. It lets your inner beauty shine through and makes you seem approachable and friendly. And as a general rule, people like to be around people who are happy and friendly. Guys are no exception. Who knows, you might gain a few friends while your at it:)
Pose. Not that kind of pose. We're not impersonating supermodels here, but that whole hands-on-hips or crossed arms stance when you're not mad is a bit of a turn-off. I mean, you don't want to walk up to someone who's got their arms crossed and is glaring at everybody for no apparent reason. Body language is a real communication tool. Just relax. Stand up straight. Pull your shoulders back. Smile. Go easy on the make up (again, we want to see you, not the artificial face), and BAM! There you go. We've got an approachable, friendly, genuine, beautiful girl. The good kind of guys - the ones who'll sign the boyfriend manual - dig that!
Be yourself. This cannot be stressed enough. Don't change who you are. Don't pretend. You are a unique individual handcrafted by God. You are special. You are beautiful. Changing that would be stupid.