make sure you eat a small, healthy snack about an hour before your apt. This advice usually applies more to if youre getting a large tat, but since it's your first, I think it's good advice for you too. It'll keep you from feeling lightheaded. a granola bar or a piece of toast with peanut butter are good suggestions.
I haven't had anything on my neck, but if it's small I can't imagine it'll hurt too much. Follow your tat artist's advice on how to treat it afterwards - there's often conflicting advice on what to do, and if you look it up on the net you will hear "never use neosporin".. "neosporin is the best". "cover it for a day".. "only cover it a few hours".. just do what your artist says to do.
Personally, when I have work done it hurts for maybe a minute, and then the endorphins start going and it doesn't bother me at all. It's totally bearable tho, it's not extreme pain or anything.
Good luck, and have fun