I recently went to one tattoo artist to do a 35 + hours piece of work and obviously I looked at all the alternative in Beijing. In the end there was only 3 real artists in town where they draw themselves and then paste it on your body (I'm talking about the owner of the shop, not their workers).

The shop I went, I thought that the price was fair regarding the detailed piece of art, colors and time spent on the table.
First thing I looked into was hygiene before even looking into his past work.

Feeling is also important with the person, dialogue has to be relatively easy because it's important to talk about everything you feel you have to tell him. Some changes on the draft, does it hurt that bad? (it does not for 90% of your body.... but some parts are tricky!). And also simple conversation... 35 hours is long...

If you're looking into a real piece of art, they should be able to provide you samples of their previous work, and I'm not talking about pictures, which can be found on internet, but actual drawing on a piece of paper. This can't lie. During those 2 months it took, I saw his new pieces, his new drawings, made me confortable in my choice.

Here is his Flickr so you can look into some of his work:
http://www.flickr.com/photos/74527882@N04/
If you are interested that's his phone : 186 11 29 69 52

Hope it can help some of you.