Tylenol is not a blood thinner, it should be fine to take before the tattoo,
the best things you can do before a tattoo is mentally prepare for it, put yourself in a pleasant place in your head,
perhydrate the day and night before and get a good nights sleep,
eat a really good healthy meal right before the tattoo,
bring sugary candy and water with you to the tattoo,
I bring skittles and M&M's,
I also bring a banana to eat half way through,
eat a little candy throughout the tattoo, it will make you feel better.
don't forget to turn the sounds off on your phone during the tattoo,like the ringer and text alerts, it's the polite thing to do.