I have a lvl 50 Demon Hunter. Let me teach you how to be a pro. Once you hit level 45, demon hunter just gets so damn powerful and literally invincible.
I have posted each skill below followed by which rune you should use in brackets. I will then provide an explanation as to why this is the most effective build.
I have also set 2 builds you should use, one before level 45, and one after 45 due to the newer runes available.
You will notice that under Devices (3rd skill), I have switched on ELECTIVE MODE (options ----> Gameplay ----> tick elective mode), allowing me to slot in whatever skill I choose.
Note that this build is aimed to deal the highest amount of damage possible, at the same time providing you with superior survivability.
Note that this build is mainly used during the process of completing missions and NOT fine-tuned for fighting bosses, feel free to adjust your skills for single target damage when fighting epic bosses.
Pre 45 Build
Primary - Hungering arrow (Scatter Shot) - Provides extra AOE damage due to the 3 way arrow split.
Secondary - Elemental Arrow (Frost Arrow) - equivalent to the wizard's "disintegrate", best skill pre level 45, rune provides +170% dmg to every single enemy passed thru + slow.
Defensive - Smoke Screen (Lingering Fog) - Skill explanation doesn't actually tell you that you turn invulnerable. Lingering fog provides you an additional 3 second invulnerability, total of 5 seconds being invulnerable. Higher cost of discipline, but no cooldowns, it is a very fair trade. Absolutely OP.
Hunting - Vault (Tumble) - Equivalent to Vayne of the league of legends, this skill makes Demon Hunter THE king of kiting. Tumble like a boss away from your enemies when they get close, and continue to wreak havoc. The rune lowers the discipline cost of a 2nd vault within a short amount of time. If you can't juke, don't play demon hunter.
Companion (Bat Companion) - Prior to my noobness I did not realise you can use Elective mode to swap in any skill you like to fully utilize the awesome customization of skills (Toggle it under options ---> Interface).
Originally, I rarely use any 3rd skills; evasive fire is just pointless when you have vault; fan of knives is stupid because you are not meant to be a melee or get close to enemies for all that matters; spike trap is alright but the 30 hatred cost is just stupid when you have Multishot as your 4th skill. So all thats left is Sentry, which is like the Wizard's Hydra. It's alright as provides you with some extra damage. I still rarely use it UNLESS I AM SOLOING DIABLO when i kite around him and it is just funny watch my sentry dealing damage while i run in circles.
Now that my noobness has been eradicated, I use Bat Companion due to the awesome Hatred regeneration, along with the extra 54% weapon damage my baby bat deals this skill is just sick. More trolling with my extra hatred? I WILL TAKE IT!
Archery - Multishot (Fire at will) - A Godsend when you see angry mobs charging at you. The rune reduces cost to 20 hatred, meaning you can spam it for "165% x 2" as a MASSIVE AOE at a massive range in front of you. Deals insane damage. You might ask, why not Rain of Vengeance? Main reason is because enemies DO NOT STAY STATIONARY and continued getting showered when you are juking around; the second you cast it and juke away, who will you be dealing damage to?
Post 45 Build
Primary - Hungering arrow (Scatter Shot) - Same reason as above.
Secondary - Rapid Fire (High Velocity/Bombardment) - Both deals more damage overall compared to Frost Arrow. High Velocity provides you with 40% chance to shoot through enemies, meaning it is pretty much the equivalent of a frost arrow BUT + 228% dmg instead of 170%. Bombardment deals some crazy mini AOE damage, 276%. Both are viable options, yes please to that extra damage.
Defensive - Smoke Screen (Lingering Fog) - OP is OP.
Hunting - Preparation (Focused Mind) - This skill, combined with Lingering Fog, is what makes you invincible. I usually only use this when i fight harder enemies. You start a fight, when enemies come towards you cast Smoke Screen to lose aggro and continue shooting at them. Cast smoke screen again if enemies move towards you again. THEN you cast preparation if you STILL are trying to kill whatever it is you are killing. This will regen your discipline overtime ALLOWING YOU TO SPAM YOUR SMOKE SCREEN AS INVULNERABILITY for a few extra times. Like I said, OP demon hunter, is OP.
Companion (Bat Companion) - Same reason as above.
Archery - Multishot (Fire at will) - Same reason as above.
Passive
Tactical Advantage - Not the best passive for a fight, but I use it because I don't like wasting time travelling through the map. However, it is STILL a good passive for juking away from enemies, or smoke screening into fights to get healing globes. I like speed, this is just my preference.
Steady Aim - The extra 20% damage is OP as long as you stay AWAY from enemies. Remember you are a ranged hero, NOT a close combat specialist. Act like your class and do what you are meant to do.
Archery - Extra damage is always nice.
Technically, to perfect this build you should swap out tactical advantage for "Perfectionist" post level 45 due to the 10% discipline cost reduction. But I don't need it because I destroy anyway.
Notes
Sometimes, it is just unnecessary to smoke screen/vault when you don't have to, especially when you can just left click away from incoming attacks and continue shooting. So save the discipline until you really need it. Of course...zooming across the map with vault and smoke screen is ALWAYS necessary :P
Remember the point of being a Demon Hunter is to deal massive damage and NEVER get touched.
I would also like to add that with Elective mode available for abuse, ABUSE IT TO YOUR LIKING! Remember a build is simply your personal preference of how you play, so use whatever works for you, and enjoy the game!
Juke like a pro, kill like a boss.