Three things to bring:
- diplomatic passport (Officials are very corrupt, so minimizing interaction with public offices is a great plus)
- a prepared stomach (the socalled potable water is definately not potable)
- a very consercative mind (I was not prepared for Costa Ricans very protectionist and racist attitude. They live from tourists, but hate all foreigners.)
What to leave back home:
- hopes of relaxing on the beach every weekend (the roads are horrendous, the cost high and the service mediocre)
- hopes of making Costa Rican friends (they are extremely introverted and although they might invite you to dine with them, they never tell you where they live)
- hopes of experiencing Latin America (except for the widespread corruption, Costa Rican reminds you more of a US-Mexican border town than of Latin America)