You should be looking for;
It should smell clean, like cleaner, not incense or candles.
There should be no animals present in the shop. (believe it or not they are carriers for things that can get EVERYWHERE)
License should be displayed for the board of health at least.
There should be an autoclave present (looks like a really expensive microwave with a latch)
The needles and tubes that go onto the gun should come out of sealed packages.
They should NEVER, EVER, touch you, the tubes, the needles, are the ink, without gloves on.
I think that would be enough to start you on. Most of the stuff is common sense. No drinking, drugging, tattooing two people at the same time, things of that nature.
Hope it helps! Congrats on your decision to get inked!