So basically i have this girl that i've been snapchatting/texting with alot, she went to the last program that i went to at my "highschool" before i changed to International Baccalaureate diploma program from economics. When we text we it's usually pretty short and neither of us know what to say until we are to the point where we say goodnight or similar. We flirt sometimes but it's not like i'm all over her but i do show some interest occasionally.

My game is pretty weak right now and i don't know how to go from here, do i just approach her in school and try to be as casual as i can and ask her if she wants to hang out/study after school? I'm sure many people are/has been in the same situation that i am in. Do i start giving compliments when we "snapchat" or similar? Should i make flirting obvious?

If it matters i'm 17.