Can Tattoos Kill You?

Only in very extreme cases and only if the tattoo artist uses old dirty needles. That's why you only go to a professional not your buddy or the friend of a friend. Visit the shop first and look around. It may sound stupid, but if the shop is neat and tidy the chances are good that they keep their equipment cleaner too. Watch them, if they'll let you, tattoo someone else. Are they changing needles? Using sterile pads or whatever to wipe with? Using gloves?    
what they're doing is basically a type of surgery. They take a needle and use it to inject ink under the surface of the skin. If they aren't cleanly while doing this you can get an infection and in extreme cases it may kill you.

One of the most important items in a tattoo shop is the autoclave which is used to sterilize the needles, grips and tubes.  Make sure they have one.