I've wanted to write (and complete) a book since elementary school. I have no problem starting stories. It's just finishing them that I struggle with. And commas. I hate commas.
I am studying writing at college. Start with a beginning and an end, then fill in the middle. Structure is very important but not as important as ideas. Good luck 馃檪
Try writing the ending first so you know what you are writing to. I'm not experienced or anything but I know that if you write the beginning without the end in mind you are kind of just following the story to see where it leads, and sometimes it leads nowhere.