Some tips for writing a synopsis are to make sure the synopsis is clear and understandable, and to format the synopsis correctly. Additional tips are to include a narrative arc in the synopsis, and stick to active voice and third person.
A narrative arc explains the plot, characters and how the book ends. It also gives agents a summary of what happens and which characters change throughout the story.
Make sure the synopsis is clear enough for the agent to understand. Mention the character identity, setting and story conflict in the first paragraph, the major plots or deeper conflicts in the following paragraph, and the resolution in the final paragraph.
Format the synopsis by double spacing it to make it easier to read. Keep the synopsis at approximately five to six pages, and write in present tense.