Warning: Love story inc.
It was a really *#%@ty tip, but I used to be really shy before, and my current gf was even more shy :P
I actually looked at her for like 4 years before we finally got together, though we both had some things going on with other people, but that was really nothing big :P So we had these periods where we talked a lot on msn (msn helped me a lot here, since I was so god damned shy), and we had these periods where we never talked to each other.
After a year or so, I started playing wow, and it was kinda good for me, because then I really didn't give a *#%@ about anything :P (she lost interest, but I wasn't interested in girls at all then anyway)
I played wow for 9 months hardcore (grinding lock to rank13 ftl), but in the end I got kinda depressed because I finally saw how much time I had lost, and how much fun my other friends had, so I quit and pulled myself together.
One night my mate asked if I wanted to come over to his place and watch a movie with some friend. Of course I said 'yeah ok' because my friends never asked me out because they knew I would just say 'busy, playing wow', so that was kinda new to me, and I figured out would be good to just do something else for once.
So when I got there, I saw the girl I've been talking about. I started to tease her a bit (randomly), just hitting her in a friendly way :P, and then I suddenly went 'o*#%@' (no, it was not an erection, but I realized my feelings for her was growing again :P.
After that I just tried to talk to her as much as possible on MSN, and at school, but not too much, because that would have been really obvious, and I was kinda scared :P
Things worked nicely and I talked to her friend about it, and got some info (use her friends!)
When I was hitting on her etc, I thought 'well, I'll just be myself, if she don't like it I'll just have to bite the pain). And it worked, even though I often told her that she didn't have the right to her own opinion since she was a woman etc :P (just for fun ofc), but she just laughed and slapped me in the face.
We've been together for 5 months now :P and everything is going fantastic.
So my tip is: Be yourself 100% because acting up just ruins the entire thing in the end, don't be afraid to say or do anything (asking for buttseckhs the first time you talk might not be the smartest thing, but you catch my drift)
Being open towards her, listen to her, and discuss with her (don't agree on everything she says), she will probably like that you actually have your own opinions!
And when you get the chance, be offensive! You're just a human anyway, everyone fails sometimes, and everyone wins sometimes!
Good luck :)