I had a leveling rule that I would never attack unless provoked. This would prevent me from unnecessary speedbumps when I would roll someone's best buddy, who would then cause me much pain by camping me with their buddy 70's. When you're leveling, PvPing is just a waste of time that will keep you from reaching your leveling goal.

Now that I'm 70, I choose not to attack unless it's a relatively fair fight, or they attack me first. It's just no fun to roll people without any risk. However, once attacked by an enemy player without provocation, they are on my KOS list FOREVER and I will not hesitate to initiate PvP whenever and wherever I see them.

People who attack while you're doing the Ogri'la memory game are particularly obnoxious and are hunted down and killed ruthlessly.