I'd like some advice. I think there's too many campers (from what I've experiencing).
just use a pdw and hold down b, but you already know that
Try anticipating where an enemy will pop up and have your cursor hovering over that area. Getting the first shot will do wonders in 1v1 battles (unless lag screws you over).
Have your cursor on him and keep it there. (That is considering you use wii mote and I consider EVERYONE to use SMGs.)