Keep it short. Book blurbs are generally not more than 3 or 4 lines and can be as short as 7 to 10 words. One popular format is to omit the subject and only write a description in several words, such as "A wild Dionysian romp--a great read!"
Use extreme action verbs. Providers of book blurbs like to promote literature with adjectives like "sizzling", "crackling" or "shattering." Then there's the ever popular "spine-tingling" used for thrillers and supernatural fiction.
Make author comparisons. New authors are generally compared to more established ones. These comparisons can be made in a second or third sentence that compliments the original style assessment.
Describe the journey. Formulas like "The author takes us through..." or "(Author) introduces the reader to..." are often used to set the stage, giving the reader a preview of the setting or plot.
End with a bang. Those who are enthusiastic about promoting a book will often include a repeated recommendation at the end such as "A must-read."