Little late, but all I gotta say is this.
Every girlfriend I have ahd has taken atleast a year after we broke up to be able to hang out with as friends again.
Be friends with her first. Don't just start going out with a chick. Tyr the wekend thing, if you can tolerate her personality and she casn yours, then ask her out. There is nothing worse then getting halfway through a date and realizing you disagree on everything, don't really find them attractive, and have the overwhelming urge to scream and walk out.
Like people have said, too much interest and they get cocky and start blowing you off thinking "Oh, he'll call back" Just let her know your interested, and she will do the work for awhile. You just have to know when to call it quits on the playing it cool and start calling her. Cause they get pissed after awhile.
Body language is a big thing if you ask me. If you can read hers, then you can read her mind. And you'll know exactly what to do.
Itrs funny, we are all talking about them like they are a different species or something.