Since Rangers can shoot at long ranges, back away from enemies and attack from a distance. They begin to attack you when you fire at them. This will not happen at a certain range. If you inflict enough damage, you can kill an enemy without it attacking you. It will regain HP quickly. However, make sure you can do enough damage. Find an enemy by walking around in stealth, then back up until it is out of view. Shoot with regular attacks in its general direction. If you don't hit it, slightly move up and try again. Repeat this until you hit it. Do not move too far or it will attack back. Note: This only works with melee enemies.