Communicating with a girl help?

[MusicMan]

I talked properly to the girl I like a few days ago and I really enjoyed it! I found that we had a lot in common. Now I want to talk to her again but I hardly see her at school apart from break but she talks to the people she knows and I'm afraid I'll embarrass myself not only in front of her but everyone else (trust me that's happens to me a lot) And I'd mainly like to talk to her mostly.

Apart from speaking face to face, what is the best way for a guy who likes a girl to keep in touch with her? I said I'd follow her on twitter so I did and I've been sending her direct messages but I've stopped because I don't know how many times I should do it, or what to talk about.
If I had a phone I could ask her for her number but I don't have a phone and I've stopped using Facebook.

Shall I get a phone and ask for her number? I don't have enough money for something like her iphone, or should I keep using twitter and save my money? I haven't really done this before and I've been quite solitary my life and now this girl has come into my life and she's always on my mind? Help lol