You use your Sign and sail card for all purchases on ship, especially DRINKS. You get a receipt to sign w/ eash purchase. CCL automatically takes a 15% tip out for you to make life easier on you (avoid carrying cash around). However if you feel like giving more than 15% to your waier/waitress or Bartender you can easily add more money to total on receipt when signing. They will be very happy. I did this a few times last month on Victory and they were very appreciative and lets just say I never had to worry about not havign a drink in my hand. Examples Prap at back pool bar knew my name for the whole cruise (from 1st hr on...) and everytime walked back there he had my drinks ready w/o having to ask. Also important to tip one of pool waiters you get your drinks much faster and often. And dont forget to tip Gabriel at Caspian bar and he will make you some mean martinis.