I have two friends that are certified to do this. One now works from home because she worked for a high-end salon and the owner stole from them and didn't book her as many appt as she wanted per day. Now she scared to work in that environment.
The other loves it and works for a great salon. I think she makes tips and then 50-60% of the cost of the service. (ie. facials there are 90 min and $80.. She would get $40-$45 for 90 minutes worth of work.)
I think it can be great but it really depends on WHERE you are going to be working.
I agree with JoceyBaby. The salon is the main thing. I used to work in a salon as a receptionist, and the estheticians were being paid by the hour. In a busy salon you would want to be paid on a commision basis, and most people give tips. I even got tipped for selling make-up a couple of times! I did make-up lessons and applications. And there is the option of working on your own, but I would build up a clientele first. I think people are usually in a pretty good mood and looking to relax when they come for esthetic services. We did have the customers who would come in screaming about a broken nail like it was the end of world but that was just amusing. I think it would be a fun job in the right place, with the right group of people.