All very good advice above but I'll add my 2 cents worth about the micro-mesh.
It's damn expensive and having lived with it for a while, I've got to say that IMHO it's not really worth it -especially for car bodies. Fine sand paper, polishing/rubbing compound and wax give comparable (maybe even superior results).
I have, however, used my micromesh with excellent results for rescuing clear parts from scratches and glue but could probably have done it without the micromesh.
Micro mesh is not bad, I'm just not sure it represents real value for money.
I'm curious what others think 'cos I could just be using it badly and not helping it deliver the goods !