Warlock is a very versatile class, but that very versatility can make it difficult to figure out the best specs for different things; today, we'll discuss the best spec for Warlock gold farming. There are really two options when it comes to farming as a warlock: Affliction spec, stacking up dots on multiple targets, or Destruction spec, destroying single mobs in a few GCDs. This guide will focus on the second option.
Your basic spec should looks something like this : http://www.wowhead.com/?talent#IcZcu0h0hZVbGVrcuVoAcct:zqT
Once you have your spec, farming is almost pathetically easy. Killing mobs with Destruction is a simple matter. Just follow these steps...you often won't reach the end once properly geared.
1. Life Tap (for the Glyph buff)
4. Chaos Bolt
5. Incinerate to finish, unless something else comes back up before the enemy dies.
The simplicity of single-target farming for warlock gold is comparable only to elemental shaman; the gigantic damage spells right off the bat really make it easy for these classes to mow down mobs. Usually you'll only need on round of spells, with the cooldowns ended by the time you move to the next mob.
You won't make quite as much as you would with a properly geared multi-target Affliction build, but the low gear requirements and pure simplicity of Destruction make it a very worthwhile farming spec nonetheless. The only gear-based concern you should have as Destruction is mana, which might be an issue if you are very, very undergeared; otherwise Life Tap should be plenty to keep you going and going.
Well, that's about all there is to say. Anyone looking to further optimize your gold earning abilities should check out my Gold Guide Review, where I compare various popular gold guides, and find one that sounds good.