Beta readers are the people who read your story or manuscript before the editors get a hold of it and point out the big (and small) problems in the story. They're not editors - and they're not copy editors - so try not to give them a crappy manuscript.
Delilah S. Dawson suggests asking your beta readers the following 10 questions:
- When did it lag?
- Did the end satisfy?
- Were the characters believable?
- What didn't work?
- Would you buy a sequel?
- What didn't ring true?
- What's your biggest complaint?
- Did the pacing work?
- What would you change?
- Can I buy you a coffee?