Welcome to inferno mode with your WD. Like all chars, before buying your gear, you need to think on your build. Never forget, usually you will have 3 builds: For fast farming low mps, for mp10 and for pvp. For mp10, y have 0dogs, bats and bears. Bears was really famoust before patch, but now people usually uses bats or 0dogs.
I will give you advice on bats build, making you able to tank mp10 easily.
Here is my build for mp10: http://us.battle.net/d3/en/calculator/witch-doctor#cTYidU!aXe!bYbZcc
Main attack is plague bats. This will do huge amount of AOE damage and will reduce damage of enemies by 20% with bad medicine passive. Bats has a inicial cost high, but the channeling cost is low, making it easily for channelling this skill forever. And his attack range is really ok for you to stand still and kill all monsters and elites around. Waller dont stop bats range !
The thing about bats is that you cant interupt it for using others skills, otherwise you will be out of mana really fast. That said, you have 2 skills that dont interrupt bats channeling. HEX (a great skill for elites fight and uber kulle) and Soul Harvest. Use Hex and Soul harvest everytime it cooldown, it will not stop bats channeling.
Dogs with life link will mitgate 10% of damage, and will take hits from mobs instead of y. Gargantuan with big stinker will trigger bad medicine as well
Spirit walk is a must for all WD, its your way out of any danger. Its a life saver skill.
Passives we have Jungle Fortitude, Bad Medicine and Spirit Vessel. You can change spirit vessel for other passive that you like, but with it you will hardly ever die.
Now that we have a build, lets gear for it:
To tank, you need to have mitgation, health enought to survive big hits and, the most important thing, you need to heal back your life fast. This means you need over 5 of life steal.
Buy a nice skorn with 5+ Life Steal, nice Crit Damage and int. With skorn, you will hit hard, will have nice life steal, and with the lower attack speed, you will use less mana and will be able to channel bats forever.
Your 45 mana regen will not be enought to channel bats. Buy a nice Zunis set. The boots with all res and the ring will be the most expensive, but the rest is really cheap nowdays.
Belt, use a nice witching hour, you dont need to worry for attack speed, care about crit damage on it and int. Try to get one with all res and vit too.
Pants, use on with nice all res and vit on it. Bracers, get one with Crit Chance, all res, int and vit. For shoudlers, get one with all res, int, vit and life %. Gloves you need int, CC, CD and all res, better with vit on it.The end game bracers, shoulders and gloves are crafted, you can try it.
Amulet, get one with CC and CD. Same goes for amulet, the best ones out there are crafted.
The second ring, i like Litany of undaunted, because of the 7% elite damage reduction. But you better use a nice hellfire ring for xp.
How to play: summon pets, strike with bats, and use hex and soul harvest every cooldown. Use spirit walk to get out in situations where you are not being able to tank. Of all elites affixes, you have to be careful with plague, the rest is easy to tank. With high Life Steal, you dont need to worry with reflect damage affix. This is a melle tank build, you dont need to worry with mortals as well.
Playing solo, your follower is a huge help. You can use Scoundrel with the weapon Buriza-do kyanon, for freezeing enemies. You can use Enchantress with Maximus, she will summon that cool demon and will help you tank enemies. Her skill that turns enemies into chickens is really helpful as well. Put a hellfire ring on then. Band of hollow whispers is a nice ring for follower as well.
The game has some "tests" to really test your char.
DPS Test: belial mp10
Tank Test: Ghom mp10
Big Hits Mitgation test: Dark Beserker elites, Skellking fight, Mallet Lords (Act 4)
If you can kill belial mp10, you have dps for all game on mp10. If you can tank ghom mp10, you have nice life steal. If you can tank a dark beserker or mallet lords elite fight, you can survive the biggest hits on game. Skellking has a WW attack that does huge amount of damage as well.
If you can pass on all 3 tests above, y will be able to conquer all quest on mp10, kill all bosses and solo ubers.
Take Care and Good Luck. If anyone wants to farm or pvp, add me :)