I have some unwritten rules:

1. Always say hello or hi when I first zone in. Courtesy makes for pleasant runs.
2. The tank gets heals first, me next, then damage dealers. Standard triage stuff.
3. Always cast Repose on multi-mob pulls if the tank doesn't pick up the healer or ranged damage dealer mobs. I catch flack for this sometimes but I rather spend a few moments cleaning up the cced afterwards than allow casters and healers to get off their spells willy-nilly. I'm an old-school WoW player. I have crowd control spells for a reason.
4. Always say goodbye.