I've used the following guidelines for our Small Group Discussion on our study with Intentional Churches and looking at our own church its good and bad.
1. Criticism is Good. A way to look at one's self and improve.
2. Critic the policy, not the person. Personal attacks are not helpful. Politics needs to learn this value.
3. Revisit the past, don't live in it. We like to think the past was the greatest thing and to relive the "Golden Years." The problem is the past is behind us and we have to strive for the future.
4. Remember the Golden Rule. Treat others as you'd like to be treated. In discussion and heated debate, respect goes a long ways.
Others you might add?