Moisturize. About one week prior to your session, specifically a long session, you want to start using lotion to moisturize the area being tattooed. Doing this will make the skin more receptive to pigment (ink).
Hydrate - and I do not mean with alcohol. If you don't normally drink much water, drink a few glasses in the days leading up to your session. This has a similar effect to the lotion and (aside from being healthy for you in general) helps to keep the skin healthy, hydrated, and primed for tattooing.

Sleep. Make sure you get a solid nap in before getting tattooed, preferably 8 hours. Coming in feeling well rested will get you in a better mindset to handle a long, draining tattoo session.

Eat. Have a good meal 1-2 hours before your appointment. It's a good idea to bring a snack and a gatorade also. When you get tattooed, you lose a bit more blood than you expect, so having something in your stomach will help keep your blood sugar level up. In turn, the food and sugary snacks will keep you as comfortable as possible in the chair.

Lastly, this may sound like some ancient fortune cookie wisdom, but I can't stress enough that you need a positive mental attitude before and during your session. The natural reaction to pain is to run from it - instead of thinking about how much it hurts, focus on your breathing and put the pain elsewhere. This basic meditation technique will help the tattoo become less about pain, and more about the sensation. A simple shift in your thinking seems too easy, but it's a very effective way to change the mood of the tattoo from tension to acceptance. You just have to let go, and let it happen.
DO NOT

No tanning, fake tanning, chemical peels, sunburns, major cuts or scrapes, in the area to be tattooed within a month prior to your session. I can’t work on freshly damaged skin...it won’t heal properly.

No extreme weight lifting in or near the area to be tattooed at least 2 days prior to your session to prevent unnecessary swelling & soreness.

Please do not bring the entire family or friend group unless they are also getting tattooed. Trust me, the process gets pretty dull after a while. One person is okay as long as they aren't interfering with the tattoo process

Dress comfortably and appropriately. Be prepared for it to be cold & warm. Bring socks or flip flops to prevent walking around the studio barefoot during breaks if you will be taking your shoes off during your session.

You are also invited to bring your own pillow for laying or sitting on during your tattoo.

I have a TV and music for you in the room, but the studio does get loud at times, so please bring some form of entertainment for yourself like an iPod, iPad, Laptop, etc. with your own headphones just in case.
Please do not schedule something immediately after your tattoo in case we are running behind or long.

Please do not use any numbing products on the area to be tattooed and please do not come in under the influence of any drugs or alcohol. For pain, Advil, Tylenol, or Benadryl are acceptable during your session.