First you take Leulier’s WoW Warlock DPS Spreadsheet and you fiddle with it until it matches your items/spec.
Then you goto Loot Rank and you enter those values in for the rankings.
Then you twiddle through the items and see what you can find. Nibuca’s Lootranks for Warlocks
Based on this ranking, Pre-Naxx10:
– Lilac has the 4th best hood and will only find upgrades in heroics.
– 3rd best belt (gogo Belt of Blasting)
– I should really get on the ball and get the 100-badge [item]Legwraps of Sweltering Flame[/item]
Of note also:
Article about a Warlock spec for leveling
Warlockery: by the numbers New scales post patch 3.1.