Steps in random order:

Tell her you've had sex: Now, don't just walk up to her and say "I have had sex," but you do need to make it clear that you have banged a girl before (even if you actually haven't). You can mention it pretty bluntly, like "yeah so I was banging this chick once and..." but she will probably be disgusted and call you a pig. That's ok. Sooner or later, she will start thinking about what you said and realize that you're not a virgin and thus know how to please a woman or at least know where her vagina is. Girls need this reassurance so they know you won't cry after the first time you have sex together. A little while after you make it known that you've had sex, she'll text you with something asinine like "so... wut r u doin 2nite lol." Score.

Wear a lot of layers: A t-shirt and jeans may feel comfortable, but girls think it's tacky and sloppy. Every girl has seen on average 45 hours of Project Runway and thus think they are fashion experts. The key to fashion is layers. Wear a t-shirt, then a long sleeve shirt over that, than a button up shirt (but for the love of god don't button it up), then maybe a polo shirt, then a sweater and two jackets with a scarf. Also buy nice shoes, but ruin them so they hold no value any more. It shows that you're rich enough to afford those shoes, but cool enough to just not give a damn and take care of them.

Have the exact opposite interests as her: If you know a girl who has a boyfriend, you know she complains about him. A lot. Mostly about how barbaric and uncivilized he is because he doesn't want to see Twilight with you and would rather watch The Dark Knight on Blu Ray. She will talk about how he listens to crappy music and doesn't read. You may think "well why are you with a guy with such dissimilar interests?" The fact is girls don't care what you're interests are. In fact, they actually love to hate your interests. Ever see some guys playing Halo, with some girls around them saying, "Ugh, this is so stupid." Girls love that. It's because each girl has a quota she has to fill each day, and failure to do so results in thunder thighs (or so the legend goes). If you try to hard to show that you have a lot in common, ("You watch The Office? SO DO I.") Then she will friend-zone you and you will be reduced to running out and getting snacks for her Project Runway party (you will be the only guy there, but that's not a good thing).

Do poorly in at least one of your c/asses (or pretend like it): The fastest way to a three-room apartment on Just Friends Ave. is by showing a girl you are smart. Straight As won't impress a girl, neither will that certificate from the President that you got at the end of the school year. Girls will think you're a dorky nerdlinger if you make good grades because she will think you don't know how to do anything but study. Now obviously you shouldn't sacrifice your grades just to impress a girl, but at least lie about doing bad on a test or something. EXAMPLE:

Girl: What did you do this weekend?
You: I had to write this ten page essay for History, I couldn't do much else.
Girl: Wow, you sound like a boring geek.

Now, even if you did spend all weekend writing a ten page essay for History (an A-? I SPENT ALL WEEKEND ON IT YOU **** you shouldn't say that. EXAMPLE:

Girl: What did you do this weekend?
You: I had to write this essay for History, but after I wrote a page I just blew it off and chilled.
Girl: Wanna go out?

Grope her constantly: No private area stuff (yet), but always hug, punch, and kick her early on. She will think it's too invasive at first, but she will eventually get used to it. Since you've touched each other before, the girl will fill more comfortable about sex since you forced her boobs against your chest countless times, so the natural progression is to do the same thing but with shirts off.

More later.