Research your book's market. Visit bookstores and libraries to read other jacket copies in the genre.
Outline a composite of the book jacket and underscore the essentials. The essentials can include a bio, a testimonial from a colleague, bullet points for non-fiction, and a cliffhanger for fiction in addition to the main synopsis.
Review your manuscript using a highlighter. Highlight passages, key words and significant or essential messages from your book.
Create a one-line synopsis of your book in third person. Draft several one-liners focusing on different aspects or characteristics of the book including a hook or compelling topic of interest.
Integrating the key words and passages, summarize your book's message in 100 words or less, creating a brief, succinct synopsis in the third person. Draft several versions of your copy to compare.
Revisit and refine the final copy of your content. Include a powerful hook to generate curiosity and capture interest.
Proofread completed content to edit typos and grammatical errors. Send printed proofs to colleagues in the publishing or genre for critique.