Flirting with a Shy Girl

Hi guys, I'm just a 19 year old kid, just entered Uni last year from a boys Grammar school, so girls/women has been a fairly new thing for me.

I'd gotten to know a few girls the past year, getting over my cluelessness, but this semester there's this one person I think I'm really attracted to. She's smart, and unlike a lot of other girls I know, if she doesn't get something, she works hard at it until she does. She's currently living off money she's earned herself (their family home's in another city). She's also athletic, has this cute face, and a smile that just brightens my day. This girl is also incredibly reserved/shy.

From what I've noticed, she very rarely talks to guys, pretty much only with other girls. I think she's also went to a girl's only college. I can't remember exactly how it happened, but sometime through the last semester, we started talking. The past semester our lectures have also finished at the same times, and we've caught the train back together fairly often (I get off at an earlier stop though). And she's actually fairly easy to talk to. I'm normally not a very talkative guy, but with her, it's pretty easy to talk, and even get her to laugh. Only, I've never really started flirting with her.

I think this may be because of a few reasons:
1) I've not really done much flirting, and have little idea how
2) What if she doesn't respond, or just gets scared?
3) She hasn't really done anything to say she's interested
4) I'm kinda scared it might get serious, and I have no idea what happens next
5) We're in a really small department together, so if it screws up, it'll be waaay awkward
6) We've been just talking for so long, will it be weird to start flirting?

Right now she's back at her home for our 3week holiday. I've got her cellphone number, but she almost never replies to texts, only when they're important. So I was thinking perhaps start next Semester?

What do you think?

Also, is there any way I can try out/practise flirting?

If you like her waiting until sept just shows her you DON'T like her.

Well, these holidays are only 3 weeks, so I'll be seeing her in July.
And I'm not really sure there's anything I can do- she's in another city right now.

You've already been flirting with her, you've got her to laugh and you got her attention. Texts...are too impersonal and not a good indication of much, there's too much of a disconnect with texting. Wait until the new semester begins, do what you've been doing, and if she's not interested in you, she'll hopefully let you know.