In game terms, any common courtesy or polite behavior which is not enforced by the game, GMs, EULA or TUA. Good etiquette is often expected in most social situations. If you break a rule of etiquette the worst that can happen is people won't like you, may kick you out of the group, won't want to group with you, and might ignore you.
The role-playing rules on RP servers are not etiquette as breaking them is punishable by a GM. However, some of the role-playing rules are based on etiquette.
Because punishing bad etiquette relies on the boor being ostracized and unable to find anyone to group with, his reputation must reach a high a percentage of the players in his faction as possible. With high server populations, a poor reputation may not spread as far and as fast. This means the tendency is, the lower the server population, the better the overall etiquette as more people know each other.
In general
- Never stalk other players, unless they are low-level newbies and specifically ask for your help.
- Do not use subjective remarks as granted on others (for example, saying "Wow you suck!" or emoting a laugh to a clear situation of grave defeat). If you're akin to talk this way, many others might not be.
- Don't force your opinions or advice on others. If you do, you come off as rude, conceited and socially inept. Some people want advice and ask for it. The rest aren't interested. The game allows for a lot of different play styles. A good player knows that. Doing 80 raids doesn't make you an expert on how others should play.
- Don't repeatedly try to duel a character when they have declined.
- When you have finished playing and you are in an inn or a city, rather than going AFK and letting the client log you out automatically, do a kindness and log yourself out. This allows other players on high-population servers that are in queue to log in earlier. In logging off, to free up space for the next player to log in to that server, you should back out to the beginning log in screen where you type in your account information, or select another server.
- Speak to someone before inviting them to a party, even if you already know the player.
- It is considered rude to invite someone to join your group without first asking. Leaving the group right after joining just because you didn't feel like pressing "Decline" is even ruder. Always practice good etiquette if you want to be invited into future instances.
- Do not bug other people for signing the guild charter. First invite them to be part of the future guild, hang out with them for a while, and then ask. Charters are not made specifically to be signed by first-mets, it encourages you to find the right people for your guild.
- If you're the leader of a group, act like one. If you don't feel like being one, propose leadership to others. Everyone is free to join or to leave, and you're not a GM to decide of the fate of others.
In chat
- Use the proper channels (General (/1)* for general chat, Trade (/2)* for trade or WTB/WTS requests, etc.).
- Politely ask questions and politely offer answers. Simple "please" and "thanks" used once in a while will bring respect.
- Don't use swear words, derogatory terms (except perhaps in jest), or 1337 speak.
- Don't spam a channel.
- Don't ask for money at random.
- Do not randomly whisper players in instances or raids to either ask for an instance run, beg for money, or ask questions that can easily be asked to someone else or somewhere else. (You can easily tell where they are using /who)
*You can change the number you use for channels (/#), so general is not always /1 and trade is not always /2.
In combat
- Understand your role (Nuke, Heal, Tank, Melee, Puller, or Scout).
- Don't train mobs, and avoid causing adds.
- Don't kill steal.
- Don't gank or grief.
- Don't bluewall.
- If you're not familiar with any of these terms, at least try not to make a nuisance of yourself in a group. If a higher level player tells you not to do something, it is probably the right advice.
In looting
- Establish Looting Rules before party gets underway to avoid confusion.
- Observe Need before Greed practices.
- If you wish to roll Need on an item, ask permission from your party members and let them come to a consensus BEFORE you select Need.
- Roll before looting a chest or container, and highest goes first. If you see a chest during combat, wait until combat is over before announcing your discovery and making your roll.
- Offer items you've looted that you can't use, but other party members can, such as:
- Don't ninja loot.
- Avoid looting until fighting has ceased. It is disruptive if a roll box pops up in the middle of a fight, especially when players must take into account whether they should need or greed that item, by checking it against their own gear, etc.
- Avoid looting if a member of your party has died and released his or her spirit or is otherwise not in your vicinity; that player will miss out on rolls and shared cash.
- As party leader, setting Loot Level to Master Looter without asking may be taken as an insult or as a way to ninja loot.