So - this is literally a post about a girl you have never even spoken to and who (arguably) may not actually know you exist?
I would suggest talking to her, firstly... Like, now.
Shake her hand, smile and say "Hi, I'm X" and just start bantering. No routines or lines.
Don't stare at her tits.
Be interested in what she has to say and screen her for IOIs (legitimate IOIs, not just ones you WANT to see, like:
Quote:
When she saw me I guess u can say she looked kinda happy to see me...
That's a garbage IOI. The girl didn't remember you from years ago, man... She was probably just smiling.
Focus on today. Maybe she's got a boyfriend, kids, a husband... maybe she's an asshole or a flaming racist or something. You have no idea. So it all starts with talking to her and screening her.
If it turns out she's a prospect and she appears interested, then you drop something like:
"Hey the lecture is about to start, why don't you give me your number and we can grab a coffee sometime"...
That's it. Don't overcomplicate it.