Relax bro, don't beet yourself up over it, cus that'll never help you progress.
I'd suggestion you read up on collage/uni game, reason being you can't do as much as you can in the field.
-Collages has friend groups and word gets around, It's almost like a big family
however next time try this out
-they look at you take there stare for about three seconds, then turn you head to look behind you as thought you though they were looking at something behind you. Turn back around, they're still looking at you, then give them a slow wave as though your trying to brake them out of a trance. this should get a giggle and most likely they'll whisper to each other.
-then from that point it up to you. You can ether escalate by beckoning them or going over. or just leave it at that, laugh and start talking to your mate and on the way out/next time you see them Open them.
what you were doing there is setting a playful 'frame' as in your not shy but nether are you running around acting like they both want to fuck you,
All the best, confidence and congruence are key and remember they're only people just like you looking for happyness.
and Q's feel free to PM me
.x.