Dont go into crusing as a "whatever" unless you understand the basics.
Basics mean if you are on ship, and your are really nice to me, and you do everything I expect of you. I will give you a big tip to make up for your crap salary. Hey thats how it works.
People serving table or rooms on 10K per year from the ship can if they are good at their job make another 50-90k in tips alone.
Age does not matter, what makes bucks is the sevice presented, and they are the people that make money