IMHO the strongest point of a lock (without any talents whatsoever) is support via HS, SS, and curses.
Then that changes slightly if you are affliction specced. Affliction is about damage to everything around you without messing up aggro via AOEs.
Demonology is about being a hunter and juicing yourpet up, send pet>cast spells>loot>/dance. Depending on which pet you use this could vary, like that rotation would be mainly for using the blueberry. The succy is about decent damage and CC. Then there is the felhunter, always good against casters. No I didnt forget the felguard, I havnt had experience with this baby, but from what I've heard he is there for damage and trying to lock an opponent up.
Last but not least is destruction. Destruction tris to be a mage having high single target damage and awesome burst damage.
Thats about all I can say, please feel free to criticise, I am still a bit of a noob and I know it.