Yes, even roleplays have rules.
1. Please keep every roleplay PG-13. There are young people here.
2. No Mary/Gary-Sues. In case you don't know what they are, Mary/Gary-Sues are "perfect" characters, who never gets beaten, has the best weapons, crushes, most stunning etc. Nobody loves them, so if you have one, kill it.
3. Don't Leave For Dead. It means signing up for a roleplay, but not roleplaying at all for a long period of time.
4. Roleplay isn't reality. Don't take insults to your characters by another player in there seriously.
5. Spam. Don't do it.
6. Don't create mini-plots without asking the creator of the roleplay first. It is very annoying for the other players and can side-track to main plot.