A blurb is very similar to ad copy.
Most writers get it wrong.

Send us a one or two paragraph description of your book. Include the genre(s), the main characters, a few sentences that summarize the plot and the challenges the characters face. Give us any hooks you feel make your book unique. Include a list of other bestsellers that readers of your book would likely enjoy. Including your current blurb is fine, if you have one, along with any hooks you feel were left out.

Simple. We write blurbs that generate interest so readers have to purchase your book to satisfy their curiosity.