Tattoos are no different than anything else, you have to tell the other party what you're looking for. When you go to buy pants, you wouldn't just say, "I want pants." You'd specify style, size, color, boot cut, low rise, worn, and anything else you want. Same thing with a tattoo. If you want an exact representation of something I'd just say like, "I'm looking for someone that will do an exact representation of this image, is that something you're interested in?" Or, "I've got something really specific in mind, are you comfortable working within those parameters?" Or, "The last tattoo I got was really well done, but there were some additional lines added and the colors weren't as close to the original as I'd hoped. Are you comfortable working with that degree of specificity?" And then show him the image you provided and an image of the final tattoo.
My artist would thank me for considering him, would but suggest I go elsewhere. And I'm OK with that. I let him know at a really high level what I'm looking for and he's exceeded my expectations on every tattoo.