Right when you hit 80, I'd say get a good frost spec going. It provided 3 percent extra avoidance, and 6 more seconds on IBF. I'd do the following spec that will help you maintain threat and have some descent cooldowns.
Talent Calculator - World of Warcraft
You can change a few points out for flavor, but mostly on trash use the following rotation.
DND > IT > Pest > Blood Tap > HB > Dump
HB > Pest > change targets and Pest again > HB > Dump
For Single target tanking.
PS > IT > HB > BS > BS > Dump
HB > OB > FS > HB > Dump