A couple of tips (my sister in law is a tattooist, done all of mine for free!)

Have something decent to eat before sitting in there. She has seen all sorts of things happen to people because they go in on an empty stomach!!

Take some Lucozade with you. She is covered from head to toe and she usually has lucozade when she has a big job done. My longest sitting was 4 hours and by the fourth, I was ready to leave!! Just take it easy and if it gets too much, just ask them to stop. That said they usually have a 6th sense as to when it's getting too much for people!