"Beta readers are an invaluable resource to indie authors. As our Laurie Boris writes, “This is someone who very nicely agrees to read your manuscript and to give you feedback so you can make improvements before you unleash your work into the hostile murky depths of cyberspace.”
Using beta readers before your manuscript goes to an editor can reduce the amount of editing needed, thereby reducing an author’s editing costs. Want to learn more about beta readers? Check out these articles before venturing out into beta reader country"
Indies Unlimited: Author Resource, Beta readers
A big collection of resources for effectively using beta readers