A few days ago, I wrote some advice on using Recruit-a-Friend without screwing yourself over in the end. Runyarusco of Unbearably HoT has some more advice for you, including a few very practical tips I missed.
Power-leveling (quite literally, in fact) multiple toons to level 60 also requires an enormous sum of in-game gold, if only to train Class skills (nevermind professions).
One thing I definitely missed out on was weapon and armor skills (there’s a reason why my hunter is out front):
The usual process of leveling a character allows for the gradual increase in both Weapon and Defense skills. For casters this is less of an issue (since in an ideal world, you’re not getting the shit kicked out of you or hitting a mob with your weapon) than melee, but even as a caster, if you get to Outland with less than 300 Defense, relatively innocuous mobs will casually rip you apart and then go back to grazing (yes, the Helboar did surprise me). How can you circumvent this issue?