Hey!
Demon hunters are not famous because their continuous damage, however, we can definitely do some huge burst damage, so don't worry.
First of all, use some enchants and gems. Period. Secondly, get your stat prio right: crit>versa/mastery>haste (this is my prio). Use potions, flasks, food: these can help maximize your damage. You have to be careful about relic choices: I prefer chaos strike runes over anything else. Do not use magic reduction relics etc. even if they provide 5-6 lvl difference.
When you are playing, it is really important to use Nemesis and Chaos blades at
