As for what to get, only you can answer that. I usually start with an idea and google the heck out of anything and everything that may be related. By the time I hit the shop I have a few pictures, generally sketches, from which I can point to certain points I like. I also show up with a color/shading scheme of what I like and don't like then let the artist do his thing. One huge mistake people make is not planning for future work, take time and think about how your piece will fit on the chosen body part and what you may get in the future.