analog

To the best of my knowledge and experience, the "scare tactic" doesn't work on most kids. They've been showing kids cancerous lungs, genitals with disgusting pus and warts on them, and films about horrificly gory road accidents, but kids still smoke, have unprotected sex, and drive drunk all the same. I've yet to meet a person who ever said a pic of something disgusting ever really steered them away from anything. I wouldn't discount it as a supplemental material (like a visual aid) to go along with an actual discussion, but I don't think "see this, this is an infected whatever. This could happen to you, so don't do it" is a very effective approach.

As for safe shops...

read this (the whole thing, great resource):
http://www.safe-tattoos.com/faq.htm

and this (especially the "safety tips", kinda boils down the major points):
http://www.safe-tattoos.com/pamphlets/basic.html

this is also good:
http://kidshealth.org/teen/your_body...tattooing.html

The above one (while the other two are great) is delivered as part of a whole range of health information for kids and teens by the Nemours Foundation. They are excellent healthcare facilities and, if you don't take the word of safe-tattoos.com (or me, since i'm recommending them as accurate), you can trust kidshealth.org.

One thing i'll say about this^ is that, at the end, it mentions "tattoo removal". Don't mention removal. One should never tattoo thinking "oh well I can just remove it if i hate it later." Always impress on your kids the fact that they are permanent. There are also cover-ups that can be done... but no one should ever get tattooed unless they're sure (at that moment) they want it forever. Being comprehensive in your fact-finding is good, but telling your teen that there are removal procedures plants a seed of "this can be undone" that you do not want. It must maintain its sense of permanency.

Remember: A concerned, well-educated parent is a well-educated child.