Tipping at restaurants, bars and coffee shops is optional. A ten percent service charge is already added to the bill. If you feel like service was great, you may leave an extra tip of your choice. Many Tamarindo restaurants add the 10% service charge and say "Service not included" at the bottom of the menu and the waiters will often add "Tips Appreciated" on your bill.

If you stay in a hotel and the bellman takes your luggage to your room it is proper to give a tip. Once in the room you may leave a tip to room service personnel and to housekeeping.

In general good manners as you would apply anywhere in the world, at least in the Occidental world. Always say hello, goodbye and thank you, keep a smile and ticos will be grateful to help.   

It is very proper to say ¨please¨, when asking for something.  Ticos appreciate politeness. 

Also to note, waiters will not bring your bill until you request it.  Your plates will be picked up, but they will not hurry you out of the restaurant.  You will need to ask for the bill before it will be brought to you.