Patrick Rhone has a great write up on what it takes to be a Mac consultant in 2013 - including his thoughts on how much to charge and how much patience you need (hint: a lot).
His most important bit of advice is something applicable for anyone doing any sort of tech support:
Also, be upfront about what you don’t know but still be willing to help them get help.
A big part of the reason I couldn't stand working in tech support is there's always someone else out there willing to lie and give out an opinion as if it's fact.
Nothing that a left cross wouldn't fix.