This disorder is associated with several vascular, neurological, and skeletal problems including stroke, heart attack, clotting, mental retardation, eye abnormalities, and osteoporosis, amongst many other complications.
Tattoo tipping etiquette, in general, should hover around 15% for small tattoos and 20% for larger tattoos, but as with all tips, you as a customer ultimately determine the amount based on the quality of service and the work performed. Consider your involvement as well.
Especially at the outset of a relationship with your tattoo artist, tipping is an important consideration. A tip that is slightly higher than average at the beginning may ensure great service and work on your next tattoo or session, or even an appointment when the office is already busy.