Spec Destruction IMO. Destruction is the most straightforward tank and spank spec. Use a voidswalker, it's easiest to play as well. Just bubble (sacrifice) whenever you feel in danger. You will need to macro your pet's ability to a key (/cast [target=player] sacrifice), because clicking is not efficient. If you want to use 'fear' effectively, you will need a mouseover macro so that you can easily fear someone who you are not targetting (which is normally the case), and set the cc target as your focus, so you can monitor the fear and know when he's coming out of it so you can re-fear or anticipate what he's gonna do. I use something like this:
/cast [target=mouseover] fear
/focus [target=mouseover]
You can set a separate macro to fear your focus target (/cast [target=focus] fear) but that may be too many keys for your nub self to keep track of.
The standard BG fight modus operandi is to fear someone who's not taking damage (cuz too much damage breaks fear), then burst damage down someone else (usually whoever's lowest on health, or a healer). And ENABLE YOUR NAMEPLATES. You can see name plates through walls, and it lets you see people's health easily for target selection and tactical purposes.
Usually people use felhunters. But, to be able to get off a good 'spell lock' is hard when you're new, and knowing the best time to defensive dispel ('consume') takes experience and anticipation as well. Succubus is usually not used, but it is used for 'seduce' which is a crowd control spell that does basically the same thing as 'fear', and shares diminishing returns with 'fear'. It has special purpose applications (like cc'ing something off of you if you're stunned or need to peel melee off of yourself, or cc'ing 2 guys at the same time).
Affliction is more about dotting up multiple targets, which requires some multi-tasking. Drain life is usually a big part of an affliction lock's play. It's where a lot of their value draws from, and that's how they survive.
Demonology is pretty tactical too, although this spec was designed for maximum survivability. There's more control, timing and positional work required in demonology. And more pet management.