Text her some really sweet stuff, and always be there for her. When she looks a little bit sad, ask her why and try and comfort her. Then slowly let her see that you love her, and hopefully she will love you back! Just don't rush it, be really sweet and say some cute things to her like : you look amazing today x or : can you help me, your so good at that! Play to her strengths, so if she's really good at a subject, ask her for help, or praise her lots!
My boyfriend is the sweetest guy alive, and I love it when he says good morning beautiful! Or something like that! Maybe put kisses on the ends of your texts? Not too many though until u go out with her! Trust me I am a girl so I know what girls like