I've never done much PVPing, but I'd like to start doing Warbands and Castle Wars.

 

What are some general tactics and skill rotations that I should focus on learning?

For Warbands the general tactic is just to join an FC and safety in numbers.  They have the gear requirements they expect you to conform to clearly written on their introductory post of their forum thread or what have you.  Unless you want to go try and pk warband looters and generally really piss people off.. :P.  As for Castle Wars...better answered by someone else ;).

Several WB FCs I've looked into potentially signing up for have listed PVP skill requirements. Things like DPS and tanking tests. If nothing else if I ever want to solo DWF camps some PVP skill might help me survive long enough to get out of the wildy.