I play a guardian since start and i have learned on thing that can help ya out is to spec Vig....you lose a few tank abilities but gain other and also you can scoop up your DoTs which will help hate...most ops fight after 5 secs you cant pull the mob off me unless i lag or something. As for HM i try to pick up the stronger mobs while DPS burns the weaker ones down...then when they done i have ample hate on whatever is left....main thing is the have your resources used right and everything goes fine

Had a group of imps. camping the shuttle from orbital station for awhile on my server.