If you are an artist, you should just try to make more unique images for friends and shops. There is a huge need for custom artwork to cater to each person's unique and individual taste.
Cartoon characters are popular, but not as popular as other things. (I think the most popular are Tinkerbell, Tweety, Taz, Mickey)
I've seen quite a few men with Taz tattoos. Also Road Runner, Bugs, Wil E Cyote, Smurfs, Jessica Rabbit, Daffy.....
Hope this helps and happy tattooing!
I've seen Micky Mouse in a variety of guises, gay Micky, evil Micky, zombie Micky, but be careful d****y can get really uptight about their copyrighted characters.
I've seen a lot of Simpsons tattoos, several full family portraits as back pieces and several lesbian sex tattoos with Marge and Mrs Crabapple. Bizarre!
There is a HUGE market for babe tattoos on guys. But mostly the style of girl is pin-ups and old school style women. Most men who get females on them don't get cartoon characters for tattoos. They aren't realistic female portraits, they are, still, animated characters, but not based on cartoons.
To actually answer your question though, the most popular female tattoo is Bettie Page.