On RC you can prepay your gratutities or have them automatically deducted from your SeaPass account OR you can pay in cash to those individuals who serviced you on the last night of the cruise. I prefer to have them automatically deducted (less cash to carry and more convenient). While there are suggested guidelines, there are no "MUSTS". Unless you count bar and wine service, where an automatic 15% gratuity is charged on your tab. If you choose to do prepay and have it charged - you will be assessed a standard amount for your stateroom attendant, dining room waiter, assistant waiter and head waiter. All others are at your discretion.