It is really hard. My daughter had a sun/moon thing on her back she wanted to cover as she didn't like it. Out tattoo guy is a fabulous artist, and he had a hard time doing it. Here is some of his stuff.....maybe you will get some ideas.Art With A Pulse Tattoo Studio | Home
Our artist is Norm. My daughters back piece to cover the sun/moon is under the large color. Looks like her backbone exposed. Not my favorite, but.....I like the peacock feather.
Also could not place which ones were my son-he has 2 sleeves, both legs, chest and back....all done by norm. Downside is he has to wear SO much sunscreen.
Anyway-maybe some ideas.