Tattoo Planes

My client has drilled me over the past 3 weeks to get these tattoos to look REAL and not cartoony. The top one was my first attempt and the bottom one the final (I hope!) Illustrator was a difficult medium to make the tattoo-like gradients. It was helpful to really think about which parts would blend into your skin color and use the white gradating into the dark ink. Have any of you made successful tattoos in Illustrator before? What was your method?