This is the shortest, sweetest guide to writing a synopsis we could find, and it’s only five steps long.
Step 1: Start With A Hook. This should be a paragraph or two similar to the blurb on the back of a book. Mood and tone is important here, use special adjectives.
Step 2: Introduction of Characters. Introduce the main characters in your book. Tell their MOTIVATION, CONFLICT, and GOALS. Stay away from detailed physical descriptions unless this information is pertinent to your story.
Step 3: Construct the Body of Your Synopsis. Here, using paragraphs, write the high points of your story in chronological order. Keep these paragraphs tight, don’t give every little detail. Remember, each scene should include, ACTION, REACTION, and a DECISION.
Example: Sam kisses Mary goodnight. (ACTION) He makes her forget she does not want to get involved in a relationship. (REACTION) He’s dangerous to her hard-earned peace of mind. (DECISION)
Step 4: Use Three or Four Paragraphs to Write the CRISIS and RESOLUTION of Your Story. Keep this simple, but make sure you show your main characters’ reactions. Don’t keep the editor/agent guessing. Your synopsis must include the resolution to your story.
Step 5: Rewrite your synopsis until each sentence is polished to the point of perfection. Use strong adjectives and verbs, and always write in the present tense. Make every word count.
Reposted from Vivian Beck’s guide here.