As with any expensive purchase, get as much information as possible. There are several excellent tattoo magazines, the best being Tattoo Burst, and numerous books aimed for the fashion conscious sold at any bookstore, especially the cooler shops like Village Vanguard.
Japan is full of inspiration, and tattooing motifs can come from the classic lexicon of traditional tattooing motifs, such as dragons, carps, phoenixes, foo-dogs and the like, that come with their own prescribed meanings, that should be taken into consideration. However, living in Japan, it’s just as common for clients to get inspired by Sanrio characters, kimono prints, and Pokémon. There is no shortage of places to look.