Some guidelines for it.
Do emote, but not overdo it. Emotes are fun and give the setting colour, but too much will make it hard for others to keep track of what is going on.
General rule of thumb with small groups: everything that can be easily heard by those sitting at the next table you can /say. Everything that you say that is supposed to be told softer is best said in one of your whisperchannels like fellowshipchannel. In a calm tavern your voice will carry further and more can be said, when it's busy the surrounding sounds will make your voice less clear so you sooner tell it in a whisperchannel unless you mean it to be heard by everyone of course!
Do try to let the other guests know what's going on. So if you are whispering secretive in a calm tavern, let the others know occasionally you are not just idling. For example: /me bends towards the group to better hear the discussion.
All OOC talk should be in private channels, not by /say