yea man of course it's worth it. almost all the hot girls i see in my school are the ones that walk past me.
u gotta be daring. call them out. "hey, are you checking me out?"
or say something like "I like ur hair/scarf", "Is that a blackberry?" that was a good one, cuz im actually interested in buying one and needed ppls opinions on which version to get so it was a win/win
depends on the situation though. if they're just looking at you, just look back at them and smile, as if ur happy to notice they were staring at you. if they wer really looking at you, they have to smile back it's like this natural reflex and works almost all the time. then just playfuly be like "hello....." sometimes they weren't really looking at you, then just brush it off, ain't no thang. don't worry about social status, or getting rejected. only losers who are afraid of doing it would laugh at you. a real man would respect you for your efforts.