My mixed team full cleared 7 instances on the way to 80, and now one-shot Culling of Stratholme last night in just the blues I got from leveling. I think I was 72 by the time I did UK, but I only wiped once in there. Other than the typical tricks people will tell you about, my one greatest trick to staying alive has been to abuse the AOE healing of my priest. When anything goes wrong, COH or prayer of healing save me big time. The priest is better than a shaman because her main AOE heal is instant cast, so therefore won't be affected by interrupts and she can heal while running. Even after the upcoming patch's 6 second cooldown on COH, with the Glyph of Holy Nova you can heal for the same amount as COH every GCD if you collapse onto her, and with Prayer of Healing I now get an AOE HOT component with the glyph. I'm not saying content can't be done without a priest, but it sure makes it easier to beat a boss your first try.