I have a great tip. It seems like common sense but many people get stuck and just start their story over. My tip is that if you get stuck make an outline. Here is the structure of it.
Outline A. topic 1. supporting detail 2. supporting detail 3. supporting detail do as many supposting details and topics as you want. This way in the end you will know what to add into your story or take out based on the flow of the outline. This works great for me I hope it helps you!