Control Warlock is my favorite archetype because Bloodreaver Gul'dan and N'Zoth both compliment Warlock nicely due to Voidlord. Against aggressive decks, you want to mulligan for AOE like Defile/Hellfire and Voidcaller/Sacrificial Pact which can summon Voidlord and shut out aggro. There is a bunch of healing in the deck to keep you alive. My winrate against aggro with this deck is very high if you get the right cards. Summoning waves of taunts is your key to victory.

Against combo decks, Gnomeferatu and Deathlord give you a chance to disrupt your opponent's combo pieces and Skulking Geist has won me MANY games against Jade Druid. Dirty Rat is the more consistent combo disrupter I've found. Gnomeferatu can be cut from the deck, but it has a chance to win you games randomly which is exciting.

HAVE FUN!