Oh, Bo has good points. :-) A big thing to consider is placement with the whole size thing. Bo said it already but it is important. :-)

"it is bound to blur" - shouldn't happen if the right needle is used and skin depth reached.

Do you have a staff infection? If you do, you will have to go to the artist on antibiotics. Or if your system is weakened in anyway. Even if it's stuff you would just let yourself get rid of naturally, your are going to have large amounts of skin cut open thusly your lots more likely to get sick(er)

And ask about they're previous work, get pictures. And NOT their drawings. Drawings can be touched up and erased and redone. Some guys have great drawings all over their shop but don't buy thin enough needles and don't have a steady hand. See if they talk freely when you ask about previous clients. If they have to think about who was actually satisfied or who has come back for more work, and what general percentage of his clients did that, then he probably never sees them again. He's obviously not going to be able to say "At least 81% of my clients would or have come back a second time" But he/she will be able to rattle off cute or touching stories, uptight people who never like anything who left with a smile etc, etc.