Let me know if this sounds like you: you have a plethora of story ideas — but haven’t really started on any of them. It’s probably because you don’t know where to start or even if it’s a good idea. If so, I’m going to tell you a little secret.
(I hope this is a secret. If not, then think about it as a helpful tip.)
Instead of thinking about your opening scene, your every character’s likes and dislikes, whether or not you want to start world-building right off the get-go… just start wherever it is your mind came up with the idea. Start at the most exciting part. Ask yourself:
What conjured up this story idea?
What was the plot?
What was the rising action?
Who came to mind?
Write the parts that compel you the most, and the rest will come naturally. The world-building, the characters, the story lines, the whole book… it’ll all weave itself together when you start at a point that actually calls to you.
Give it a try.