You could get the traditional crescent and star design, or your favorite passages from the Koran done in fancy Arabic calligraphy. Any design that is personally meaningful to your faith will be good.
Good question. Since tattoos are very much taboo to Muslims in general, one would expect that any tattoo depicting anything Islamic would be insulting to any Muslim seeing it.
The term "good" is subjective. It really depends on what you want. No one could tell you what Islamic phrase to put on your body. It's your body, your tattoo, it's up to you.
