Having twinked several characters at 29 and 39 and then STOPPED using them to level my warlock, I waited until 47-49 to run BGs, and only to get the Dryad Bracers and Highlander Boots (+12 stamina enchant), because I'd geared up the rest of me very well. Warlocks are awesome at PvP:
Fear, DoT to oblivion, Life Tap, Drain Life. Drain Soul. Gain Soul Shard and 15% of mana back. Blood Pact to return to 100% mana. Next target.
Multiple targets? Improved Howl of Terror, Siphon Life and Corruption as many as possible. Drain Life until Nightfall kicks in. Instant Shadow Bolt, then Fear, and then run and hope the others haven't caught up to you. If I die, I've already soulstoned myself, so when I pop back up from the dead, I'm sure I get a "WTF?" reaction, when the lone player standing over me to do a /spit or /laugh gets Fear, DoT'd and then drained to death... followed with my own /spit or /laugh. Keep your healthstone up, acts as another potion. The possibilities are endless.