Roll a hunter.
Lol, seriously though, I think hunters are the most OP class in lowbie BGs. They're the easiest to twink out, and with the change to concussion shot (you can now keep someone perma-slowed, wtf blizz?) you don't really have to worry about people getting into range.
I normally drop a freezing trap (whichever one it is, the one that iceblocks someone) and stand with it right behind me. Then I basically just turret. If a rogue sneaks up behind me, they get trapped, I move away, and turret them too. Simple, effective.