HOW I DO IT ...

Well, that would be telling, but here's a general outline:
1. I use my extensive knowledge of MacOS versions 7, 8, 9 and X, and formidable skills and intuition, to diagnose the problem and develop a plan of solution.

2. I use some of the best software available to repair problems with software stored on hard drives, the causes of most Mac problems.

3. I explain problems to the client, tell them how I will repair the computer, and tell them what to do toe prevent the problem from recurring.

4. I attack the problem with vigor and quiet, focused ferocity. I can't solve every problem I encounter, but I solve most of them, and client will know I did my best.