Open the synopsis with the main character, whoever that is. Give some clue as to the setting. Introduce the main external conflict and the main internal conflict.Follow both arcs, external and internal, from beginning to end. Include two or three major turning points, then the climax and resolution. Leave out any character or event that is not directly relevant to the synopsis story. That includes sub-plots. Use as few characters as possible and only name those who play a role in this version of the story.
In other words, simplify, simplify, simplify. No one reading it should have any trouble following the story or understanding what is at stake. Synopses are not just about what happens. They're about why things happen. The emotional core. Make sure you include that.
I may even be able to do that. The idea of simplifying and just picking the main arc for the synopsis echos the guidelines for writing your pitch or query. Find the core conflict, the catalyst that starts the story and use that arc. I guess after writing 80K plus words it's hard to simplify but it's gotta be done. Hope this helps anyone else that's working on a synopsis. And if you are, good luck.