Here’s an article I’m going to be studying. You might want to take a look, too. It summarizes what sends up red flags for readers (agents or not).
If you have started your book with a prologue, here is something you should read from Kristen Lamb. Her entire blog, by the way, is fantastic!
From an editor, here’s a well-thought-out post on the pros and cons of prologues from a contemporary point of view. It starts with the pros. which, if you have used one, you already know. Keep reading. You may need yours, but you do need to know why they are less common in contemporary fiction than in works written 30, 40, 0r 50 years ago.
Good sense about prologues from author and former agent Nathan Bransford.
Check your opening and make sure these two reasons do not apply.
Click on the link above to learn how important it is to begin your book in the middle of the present moment rather than with a flashback, background, or “thoughts.” Mary Kole works with writers of works for children, but the principle applies to all contemporary fiction. You don’t have long to draw your reader into the story.