In no particular order:
1. Never fake an orgasm. It ensures that we'll keep doing whatever it is we're doing wrong (if anything). You don't enjoy it. When we find out, bad things happen with the relationship. (Though we might be touched that you wanted us to think that we were effective.) Besides, unless you're really good at faking it or the guy is really dumb and/or ignorant of female sexual physiology, we'll find out sooner or later.
2. Don't play mind games with us if you're trying to get us to ask you out. If you do something which makes us think that you're not interested and keep this up for a while, or if you engage in very contradictory behaviors, most of us will just blow you off.
3. After we're in a relationship, don't play dumb mind games. These include "Do I look fat?." Also included are things like "Do you think she's attractive?" because we can't win no matter what we say.
4. We like you, but that doesn't mean that we have to spend every waking moment with you. This goes double if we have something else very major going on like graduate school.
5. We like to receive odd little gifts and stuff too.
6. Sometimes we like to be the recipient of a romantic evening or romantic outing. It gets old if we're always initiating.
7. You won't change us. If a guy is an asshole, he will remain an asshole. If he's a nice guy, he will tend to remain one unless you somehow manage to convince him that women prefer assholes.
8. We like to be hugged and kissed too. Women don't have a monopoly on this.
9. Realize that it is human nature to look at members of the opposite sex. You do it too, and you know it, so don't get mad at us for doing the same.
10. Guys like sex. However, we don't like it when you sleep with us too soon. Sure, we like it at the time, but then we start to wonder how many other guys you've slept with.
11. Contrary to contemporary belief, some guys -- if you like guys who put some emotion other than lust behind things -- actually like it if you don't have sex with them until you're in a long-term relationship of some type. What kind of guy you're dealing with should be apparent pretty quickly in a relationship. This doesn't necessarily mean that they want you to be a virgin until marriage, but this kind of guy does prefer if you're not that experienced. (You'll get enough experience with each other later anyway, and neither party is sitting there comparing the other to past partners.)
11. We aren't nearly as perverted as you think we are.
12. We aren't nearly as horny as you think we are.
13. Just because a guy doesn't give you a look like he wants to jump your bones and asks you out doesn't mean that he isn't interested.