What do you need to be a tattoo artist?
There are a number of things that you will need before you can enter into an apprenticeship with an artist, and the number one quality to have, is a genuine respect for the field of artwork which is tattooing. You will waste the time of yourself and of your teacher if you want to get into it solely to get famous and to be "that guy" who does tattoos. For those of us serious about the profession, it's more of a calling than a thought out idea to get into tattooing. Having an undying love of art, the unrelenting self improvement of your craft and techniques, as well as the ability to compose yourself as a professional in the professional art world are all very vital aspects to it.
Since it is a labor of love, those strong enough to make it in this industry are relentless self promoters and have what it takes to ride the uncertain economic waters of tattooing. During the tenure of your apprenticeship, you will not get paid a salary of any kind, but better shops will at least "tip you out" for your time and gas but this is not always the case. Also, unless you are in a rather good location, your business will be a bit sporadic in the first year or so of tattooing until you build a name for yourself, but this goes back to the self promotion aspect of the business. Before you contact an artist about retaining an apprenticeship, read everything and anything that you can about tattooing, the history of it, different techniques, educate yourself in bloodborne pathogens of the basic kind, being certified in CPR and first aide will greatly improve your chances of getting the position as you will have to get certified in it after the fact anyways in addition to being certified in bloodborne pathogen training. Get your up to date hepatitis and tetanus shots if you haven't already and get documentation to this effect, once again, you will be required to get these once you're hired anyways. You don't have to worry about buying any gear this early on, since your teacher will ensure that you buy quality machines and supplies, and not cheap knock offs.
Doing all of this will greatly help you to become a competent and well rounded artist with a bright future as opposed to being just another shark in the water. Best of luck.