i know several people who have started their own tattoo businesses, one who currently owns and operates 2 different locations. that guy in particular started by apprenticing in an established shop in a resort town, then moved and opened up his own place with a small business loan. he's opened and closed several tattoo parlors in different places. he tells me that he relies on word of mouth to get customers initially, so he makes a point to involve himself in young-adult social scenes and self-advertise. his business model is like this: move to college town, ingratiate self in college party scene, tattoo college kids. business starts slow then picks up as word gets around, then tapers off as most everyone who would get a tattoo has already been tattooed. when it gets hard to pay the rent, he closes up shop and moves to another college town and starts cycle over again. he's been doing this about 15 years or so, and while it's not stable, it's been successful.
i know another guy who's sort of doing the same thing with his own business, and another guy who is a really talented artist who is following a similar model but he's not interested in owning his own place. instead he keeps getting hired on in different parlors, which all last some years, then saturate the tattoo-getting population and eventually close down for lack of new business.
i only know of one tattoo parlor that's been open for more than a decade -- and they don't rely only on tattoos to stay in business... they've gotten and lost liquor licenses and have a somewhat steady side business selling leather jackets and gloves etc. for motorcycling, and frankly been in court over and over for drug and moonshine trafficking. tattoos alone don't pay their bills.. watch out for that =\
i think that unless you are in a place that sees a regular big turnover of young, transient population, like a big college or resort town, it's very hard for tattoo/piercing businesses to stay afloat. it is not like a grocery or hardware store, where you make sales with the same people for years and years - except for a few, most customers are one-and-done, and even the ones who eventually tattoo their whole bodies run out of skin at some point. if you are in a very large city you can overcome the finite customer base issue somewhat, but you are also in competition with a lot more other businesses already established.