If you can get a lock summon at 55 to the HFP instance stone, don't stay in Strat until 58. As soon as you hit 55 goto outlands, you'll be 60 in 1-2 hours.

Also be mindful in Stratholme undead side, take the ghosts out first they like to silence.
Also be mindful of Eye of Naxx!! I can't count how many times poor AcidBurn was taken out by a gargoyle.