Here is a little trick that has helped me when writing longer prose pieces - wish I could remember where I picked it up! You'll like it because it's as simple as A B C D E.
A - Action (always a great beginning)
B - Background (who is your character, what has already happened that will help up understand what's going to happen?)
C - Conflict
D - Development (the heart of your book)
E - End (a.k.a. conflict resolution)
This is a great outline for those who don't believe in outlines. I hope it helps you as much as it's helped me!