I'm currently running 1-4 man groups in act 3 Inferno, and I thought that some of my experience could really help some of the up and coming Demon Hunters out there.
With my play style and build I almost never die now despite the random super fast molten shielding mortar house wall mobs (which I still usually get away from), so I think I know a thing or two.
My Playstyle
When I solo Inferno I grab the Templar and try to gear him with a good mix of % Life, Vitality, and Strength for damage mitigation, but honestly having a companion does almost nothing for you besides giving you another smoke screen target, so do not rely on your Templar to tank as he will probably die 95% of the time on pulls. I always use the stick and move tactic meaning I will shoot as many frost arrows as I can at a set of mobs, and then when they get within a few feet of me I will smoke screen and continue to DPS if I can burst it down quick enough or I will reposition and then continue to rinse and repeat.
Solo and general survivability:
You have to remember that you are not going to be able to take even 1 hit from anything without dying early on before you get all resist and better armor/dex items, so learning to dodge skills and watching the enemy mobs for their animations when doing said skills is key in surviving inferno. Using Smoke Screen as often as possible will save your life, and sometimes standing still and seeing the hit come towards you then Smoke Screening at the last second while continuing to DPS is your best option just remember that repositioning isn't always going to save you, and remember don't be afraid to leave people behind if they pull a bad pack of mobs you aren't going to survive a 13 mob pull with 2 blue packs most of the time period.
My Build
http://us.battle.net/d3/en/calculator/demon-hunter#biXVlh!cYe!aZZbbZ
Why these skills?
Entangling Shot w/ Chain Gang
A free AoE snare helps you kite mobs easier when you are out of hatred, and the added cull the week damage in AoE form is unmatched in 90% of situations this skill is a viable tool to defeating inferno as a DH.
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Elemental Arrow w/ Frost Arrow
If you have mained a DH for any amount of time and have had your chance to get your hands on this skill you would know that it is by far the most op damage skill a DH has not only does it only cost 10 hatred, but it deals AoE damage, snares, and synergies with cull the weak.
Smoke Screen w/ Lingering Fog
If you have made it to hell yet and tried this skill while you were about to die to some sort of AoE or single target hard smash you have probably already found out that this is the most overpowered skill in the game at the moment, and is the core skill for any DH.
Preparation w/ Battle Scars
Preparation is unmatched by any other hard discipline skill and w/ Battle Scars you get a free potion every time you use it. I have tested out other runes, and nothing is more valuable than healing yourself for 60% of your health when you are about to die on top of resetting your discipline so you can Smoke Screen more to try to burst mobs down.
Rain of Vengeance w/ Stampede
AoE knock back that costs nothing is a very nice skill if you are running solo, and sometimes even in a party, but I usually run Marked for Death with the Reaper rune if I have any type of decent teammates with me because of the amazing AoE damage + helps burst mobs down faster.
Companion w/ Bat
This is an obvious staple in any build the hatred regeneration is unmatched by any other skill you can stick in the slot, but your Bat sometimes pre-pulls pack so be careful ^^.
Passives
Cull the Weak
Frost arrow and Entangling Shot are your 2 core DPS moves so this is a no brainer in most cases, but I actually have this swapped out right now for Sharpshooter because I'm using a 2h Crossbow and the critical damage is insane in comparison, but I would highly recommend using Cull if you have any other type of weapon.
Steady Aim
Some people think this is a useless passive at times, but if you play correctly you can keep yourself out of range of most mobs by smoke screening and positioning correctly to make this a viable choice, and in all cases with party members or without party members I have found this unmatched.
Archery
This is your staple passive for doing damage with any weapon see Cull the Weak above for variations on switching out Cull:Sharpshooter.
Gearing
When I first came to inferno I thought that stacking vitality would save me, but doing so will not save you from anything because most mobs will 1-3 shot you either way unless you have the following stats. Remember that you are going from hell to inferno which means you are going from using a 200-300 DPS bow to a 500-1.5k DPS bow, and the gear scale is just way higher than what you will find in hell, but if you give it time and farm Act 1 a lot you will get the viable gear eventually to get all the way through inferno like a pro.
Dex
This is an obvious choice as it increases your DPS, gives you dodge, and if the mob is dead it can't hurt you.
Resistance to all elements
This is by far the greatest stat you can invest in hands down because most of the damage you are going to take is elemental this will increase your survivability 10 fold, and I'm not talking about 10 or so Resist to all I am talking 300+ Resistance to all elements will change the way you look at inferno forever.
Vitality
Now I know that I said this stat is the devil and it will trick you at all times into a false sense of security, but what I ment was stacking this stat alone will do nothing for you, but getting a good amount of health (I have 25k health and 300+ Resist all w/ barb shout in A3 Inferno) and Resist all will give you the ability to take 4+ hits from a mob which is great considering you can just smoke screen after the first hit and recoup.
Armor
You should never discount this stat as it is a very viable mitigation tool that will allow you to get to the point where you can face tank some mobs (Yes I can face tank some mobs in Inferno), and if you use a 1hander with 550+ DPS w/ a shield until you can find a 800+ dps 2h w/ a mix of other good gear you can mitigate a lot of those 1 shots early on into 2-3 shots (I generally look for shields with resist all, high armor, high block amount and DEX. Remember that even though armor is valuable if you aren't doing enough DPS to kill mobs you are dead anyways, but losing 1k-2k when you have 15-50k DPS isn't a huge loss when you get that survivability from a shield.
Magic Find
Obviously the last thing on the list of stats, but will help you get items faster.
Extra Note
Having trouble with reflect mobs? Try using Shadow Power with Gloom. It will help you a lot.
