GOW multiplayer help

Since I am taking a little break, I've been playing a lot of GOW. I started to play some ranked matched of multiplayer. It is really frustrating! I've been getting owned (or Pwned or GOWned or whatever the lingo is today). So, I'm looking for some tips. I've memorized the maps. I also figured out where the various weapons are on each map. I've learned to keep moving at all times. I've learned to look behind me. I've learned to stick with my group. I've learned to talk to my teammates. But, I am having a hell of a time getting kills (my max is 5 in a ranked match). So, I thought I'd have an open forum for advice. OK you gear-heads, what should I be working on?