1. We do not have a one thread per user or month policy.
You are allowed to have as many as you wish. However if you have several artworks ready, please post them in a single topic.
There really is no point in making 5 new topics in a row.
So to sum it all up: feel free to post as much as you want, but don't spam.

2. If a user's work sucks tell him. This is the only way he can improve.
Don't be shy. You don't have to be rude, but you should be honest.
Nobody benefits from comments like "Maybe the light is a tiny little bit too weak in the top left bottom right hand corner. But perhaps that's just me. :-)"

3. That's about it. I honestly can't think of anything else. Have fun.