I'm in high school and I know teen relationships are basically practice and I have yet to have a serious relationship but I really tried at this one

OK, I've been flirting with this girl for a while
And after a couple of weeks I asked her out, she said she'd think about it and never answered so I talked to her on and off for a couple months

I was thinking of asking her to prom, and suddenly another guy (whom I couldn't see being liked by anyone) asked her out and she basically told him that because I didn't ask her earlier she would go with him

This really pissed me off, I really don't care that she's going to prom with another guy but the fact that she actually did like me but waited until prom to even consider it

And lately I tried to talk to her again and she actually started talking nicely again,
She's playing with me and I'm messing up along the way

I don't know how informative it was, but could anyone give me any advice

I've thought of asking her on a date, but I would fail
And I've considered asking her to a group date kind've thing (going to the movies with friends) but I still might not get to "Talk" to her, if she even goes

I wouldn't look at it as a practice relationship. Some turn out to be pretty serious.

Anyway, sounds like she already knows you well enough to decide whether she likes you or not. So I think that you can just go for it and ask her on a date.

If she says yes, then great! If she says no, then you can move on and forget about her.

I know you might like her a lot, but there's no point wasting your time waiting around for a girl who doesn't feel the same way about you. You could be spending that time with another girl who actually likes you back.