I have 5 tattoos and of them the one on my calf hurt the most (the bottom of it is close to the bone.) The rest are on meatier parts of my body, shoulders and chest and they hurt, but not bad. It's all relative, some people have very low pain thresholds (as do I) and some don't. It's like Nix said, tho, it's a good kind of pain. It'll linger in your memory for a while, but a couple months will go by and you'll have forgotten all about the pain and be thinking about what you want to get next. They're addictive! Generally, ones that are on very sensitive parts of your body; stomach, underarms, back of the knee, etc., and ones that are on bony parts, hurt the worst. I have a friend who has an awesome butterfly on the top of her foot, and she says it hurt like a ***! I can believe that! Anyway, before you do it, make sure you REALLY want to.....that's kinda what makes the pain bearable.
As for after-tat care...you'll need some kind of ointment, I always used Bacitracin, it's an antibiotic ointment. I've seen people use PrepH, too. The main thing is that you keep it moist while it's healing. Crusty = bad. You don't want it to get scabby, it'll cloud the colors later. Think of it this way, the tattoo is a scar, literally. When you get a cut that forms a scab, that skin that grows back underneath the scab is not the same as the rest of your skin. That's what you're trying to avoid, that scar tissue. Usually takes about 4 - 7 days before you can kinda ease off on the ointment. The artist will give you tips on caring for it while it heals, tho. Or at least he/she should, if it's a reputable shop.