bit of basic info first: 18 yo male, average build, height etc.

Between the ages of 15-17 i used to be pretty good at getting girls, could always get on with them and i've slept with around 15 girls. I didn't really pay much attention to girls for a while but when i turned 18 i thought "right now i can go out there and try and pull a bit". anyway here's my problem: every time i see a hot girl i never have the balls to initiate a conversation and it seems like all my mates get all the girls (doesn't exactly piss me off because i think "fair play" but it does get a bit annoying sometimes) anyway how do i (average looks) become just as attractive to girls as all the other lads out there?