The purpose of a title is to give a potential reader an idea of what a book is about. For this reason, you want your title to say something specific enough about the story, but not enough as to give away the ending. It might be a good idea to finish the story (or at least have a good idea how it progresses and ends) before making a title.
Well, it depends on what actually happens in the book. Maybe it could have a character's name in the title? Perhaps you should wait until you've actually finished it and then think of a name. :)
it all depends... if u send me the book i can give u a better idea.... my friend and i are writing a book together, and i'd love to meet more authors! We called our book Stark's Angel, because it's about a guy named Stark, who tries to kinda capture/seduce a girl named Angel... i'll send u ours if u send me urs!