My God. I haven't been on here in awhile and I just realized how rediculous some of this is. I CAN'T believe I used to talk just like most of the people on this message board. STOP OVERTHINKING THINGS. Holy ****, when you show up and she's the only one there you are in luck, my friend! You could have totally just chilled with her/made a move.
OK, when you are at a party, note the word PARTY, assuming people are drinking that is. That means that since it's a party, you can do rediculous things you wouldn't normally do. You can hook up with 5 different girls if you want.
Heres my advice of the day: Get a way to stay out all night, and go to a college party. Any college party. It doesn't matter if you don't know a single person there, you can always bullsh it if you need to. Get drunk, talk to people, watch other guys that know what they are doing. Repeat that like 20 times and you will be awesome at quick hook ups. I promise.
As far as starting a relationship... Find someone that is good at them and talk to them about it. You gotta hear it from the people that know what they are doing.
DON'T GIVE UP!!!! KEEP YOUR HEAD UP AND KEEP TRYING!!