This in-depth article by Sheila Kelly sets out step by step how to write an effective synopsis for your novel.
Author Ebony McKenna gives some helpful advice on writing a novel synopsis.
7 steps to writing an effective synopsis. This post gives advice on how to avoid ending up with a boring summary of your story (‘and then this happened and then that happened’), and tells you how you can include the emotional twists and turns that make your story interesting.
A break down of the key elements needed for a one page synopsis. Includes worksheet.