What equipment needs to be sterilized?

I'm going to be teaching some kids in my youth group about tattoo saftey and just wondering what parts of the kit need to be sterilized/replaced after each application of a tattoo? I know that it is anything that comes in contct with bodily fluid, but does that include the entire machine as well if it gets splashed with blood? I know that needles, tips, grips, and tubes need to be sterilized, but what are they exactly, and can they all just be replaced? And what are the best methods of sterilization?