Having a little trouble here

Hey my name is Luke, first of all im glad to be able to ask someone who can hopefully help me out here. Im a younger guy, 19 and id say i think ive got the looks part and my personality down.. but my problem is when im trying to start a convo with a girl ive exchanged a couple looks from and i know there could be some connection. For instance today i was at a restraunt and i was noticing a waitress and she noticed me, there was a little small talk at the table but i was with family so not much i could do right there. I was gonna go up to her on the way out and invite her to an imaginary party at my house later after the game that was on, i was gonna say that so i could have a quick way to give her my number and then walk right away. on the way out i noticed she was sitting on the inside of a group of 4 other waitresses there and instead of going up to her i followed my family right out and knew id beat myself up about it, which is true.  Ive had similar situations where theres a good lookin girl but i just dont force myself to say anything, ill be honest i think its because i dont have the courage sometimes, ive had a girlfriend before for 2 years but nothing since, its been a year. and im very ready to talk to someone new. please help with some advice if possible, thank you!!