Join one as soon as possible
The reason probably isn't the one you think. Yes, of course you join a critique group for the opportunity to have your work read and to get feedback on it. That's important. (A little later, I'll give some advice for receiving a critique.)
The greatest benefit of joining a critique group is the opportunity to read someone else's work and to give feedback on it. If you can figure out why someone's story isn't working, then you'll be able to apply that lesson to your own work. It's much harder to analyze why something works. Good writing and story telling is seamless, you can't really put your finger on it, it just works and it's awfully hard to learn lessons because you're too busy enjoying the story. You might pick up some good techniques, but figuring out what went wrong is going to be a zillion times more helpful.
Never argue or defend. Both will keep you from seeing that your hero isn't believable when he does X. He can still do X, you just need to work on why he does it.
Doing a good critique isn't easy. It's hard work and can take hours and hours. Hours you could spend writing your own story. Ask yourself if you want to be published. If the answer's yes, then do the critique and don't cheat anybody of your time and effort.
How To Get the Most Out of Critiquing Someone Else
- If something isn't working, figure out why.
- Analyze in detail.
- Provide the answer and propose a solution.
- Be specific. It's not enough to say the heroine is immature. What choices did the author make to give you this impression?
- Identify places where the story starts to droop. You'll feel it when it happens. Now figure out why. What would you do to fix it?
- Analyze the big picture. What do you see/feel when you envision the characters? Doing something different? What?
How To Receive A Critique
- Take a deep breath and let the shell of the turtle cover your ego.
- The question being answered is "What effect did my writing have?" You need to know the answer in order to know what, if anything, you need to fix.
- Never argue or defend. Both will keep you from seeing that your hero isn't believable when he does X. He can still do X, you just need to work on why he does it.