Since Rangers are able to shoot long range, you can back away from enemies
and attack from a distance.But they will start to come to attack you when 
you fire at them.This will not happen at a certain range. If you have enough
damage,you can kill an enemy without it attacking. It will regain HP quickly
though,so make sure you have the damage to do it. Find an enemy by walking a
round stealthed, then back up until it's out of your screen's view.Shoot with
regular attacks in its general direction. If you don't hit it, move up 
slightly and try again.Try this until you hit it. Don't move to far though 
or it will attack back.This only works with melee enemies, not ranged.