Make sure that when your weapon is drawn that you only target enemies, use L1 + up and down on the D-Pad to cycle through enemies in your enemy list, this is easiest especially in a group of enemies and you trying to target one specific on. Also take your time to practice on the controller since some people say the targeting is difficult, but it really isn't just takes a bit of time to get used to it. I use a control to tank and never had a problem in groups before.