Has anyone had any experience with permanent makeup/eyeliner?

I am a permanent makeup artist. My clients love my work. Get referrals from other people that have had it done. Ask to see pics of the practioner's work. I prefer to start out conservatively. I bring my clients back 3 weeks later to examine the makeup. If any corrections need to be made I do it at that time as part of the service and it's a no charge to the client. Usually, if I have any corrections it's adding more eyeliner.
Get the practioner's credentials. I got my cosmetology license in 1977. I worked as a makeup artist until 2000. I also got my dental hygienist license in 1988. When I decided to become a permanent makeup artist in 2006, it came naturally to me. I had skill in makeup artistry and a flare for small detail that I picked up as a dental hygienist.
Word of caution, just because someone has a certificate to "instruct", doesn't mean they are good at it. Ask lots of questions.