Etiquette Questions.

[Yarikh]

I think most people welcome random heals when their hp is down to half. And help only if they're struggling to kill something with their health bars being low. Or if I see them getting aggro of two mobs, I put the other one they're not currently attacking to sleep.

There are some quests that require you to have a monster to near death before using a key item on them so I don't advise helping them finish them off, especially when they don't look like they're having trouble with it. There was this black mage that probably thought he was helping me by firing at my targets the other night causing the next following spells to kill them instead. Not sure if trolling or if he was on the same quest and didn't know he wasn't supposed to kill them.

[HEC]

There are some quests that require you to have a monster to near death before using a key item on them so I don't advise helping them finish them off

That's most unlikely to happen (unless you're in the group with the player) as when you attempt to attack (a vaste majority of) leve quest related mobs it will fob you off with notification "the target is part of another's player duty". You can also recognize by icon on the player if (s)he is in the duty at the moment or not.

In principal (as healer) if I see anyone running away from mob with life bar very low I'll atemp to heal them or (worst case) raise afterwards.