I wasn't getting ready for surgery or anything, but after having a colonoscopy my Dr put me on azathioprine, not to mention just having autoimmune diseases, my immune system is always non existant, I get infections very easily, and all the time. But it was the anniversary of my brothers death, and my sister and I got matching tattoo's in his memory, it is the first and only tattoo I've ever gotten. We talked to the person who was doing the tattoo and made her aware of all of my health problems, and my compromised immune system, and all the infections that I had. Of course she warned me about the possibilities of possible infections, and told me that if I felt my tattoo was starting to feeel infected to go strait to my primary care doctor and get on antibiotics. But I did get my tattoo, and I had absolutely no problems what so ever. Infact not only did it not hurt, but it never even pealed (my sister had problems with hers pealing and hurting when in the sun light) We were told to use Eucerin Aquaphor (you can pick up in any store, in the lotion section for less than $5) that worked great.
Of course not everyone is the same, but like they told me, if you feel like it's getting infected, just get in to see your Dr ASAP, or if you're worried about it maybe see your Dr first and maybe they would advise you to start antibiotics before having it done.
Hope this helps,