How can i get close with this girl?

i really like her and it's been a long time of plotting on how i can get close with her. she's not that type of girl that likes guys who just walks up to her and says hi or what on a bar. she's not also that type wherein you can just send her a message on fb. recently, i unintentionally got to know one of her friends, but every time we see each other, we just give a casual hi/hello to one another. i've thought of asking her friend if maybe she can help me out with her friend, the girl i like. but it's still inappropriate to ask her since we just met and not that close. what should i do? i cant think of anything that might work. i don't want to mess this up since she really is a great girl. i rarely have problems with these things. but this time it's different, i'm afraid to mess this up, that's why i can't think of anything. btw both of us are 22 and have different professions.