I do mobile headlight restorations primarily. I am just getting into detailing (because I do it on my car and enjoy it). Just did a older 2000 XJR this weekend and the customer thought it looked like new (Gotta love that).
I did not get into it JUST to get detail customers, but I had thoughts of possibly doing full detailing too. Vision for where you want to be is key. I like how much faster the headlight only side is, but I LOVE full detailing too (It's just so much harder on my body)