
buying a ticket
Buses are plentiful and very cheap. For an hour travel you will pay about 500 colons or a dollar. There are no roundtrip tickets. Buy the return ticket after you finish the first leg. If you are at a bus station you buy the ticket and you get a seat assigned. In rural areas buses will stop for you almost anywhere if you hold out your hand. Usually you pay when you get off.
seating
If you have a choice of seating get a seat that will be more out of the sun. If you have a ticket you sit in the assigned seat. If someone is already there it is normal to ask them to vacate the seat for you. Disculpe, es mi asiento is the appropriate phrase. You may be asked to swap seats so couples or family members can sit together. This is fine.
The first seat on the buses is reserved for older people, pregnant women, people with handicaps. You may sit there but it is possible that you will have to give the seat up.
luggage
On the bigger buses, large pieces of luggage go in the underneath compartments. They will accommodate large items such as bicycles and surfboards. It is nice to sit where you can keep an eye on this luggage when people get off. Keep your hand luggage in your lap. If you must keep it in the overhead bin, put it across the aisle and in front of you so you can keep an eye on it.
bathrooms
The bus stations usually have bathrooms. The buses do not. If you really have an emergency you can ask the bus driver to stop. The helpful phrase here is: tengo que usar el baño. I have been on buses that did not have a break for over 4 hours so think about how much you drink before and during the ride.
fellow travellers
Taking the bus and hitchhiking are the best way to meet local people. Most Costa Ricans are happy to strike up a conversation. If you are not sure where to get off the bus this is a good way to start a conversation.