Do and don't in Costa Rica

Do learn the local language and don't expect things to be like they were wherever you came from.
The best advice I can give you after being here for over 15 years is, instead of purchasing and studying guidebooks, invest your time and money to learn Spanish.
Books are simple to purchase but they will not enable you to understand the Costa Ricans and adapt to their society.
If you learn the local language, then you will be able to communicate with the Ticos, gain their respect and truly understand them and their culture.
If you're expecting things to be the same as in your home country then you're bound to get disappointed. A move to another country allows you to start over with a new life and experience a new culture in a new environment.
Most foreigners have become accustomed to things such as promptness and efficiency. That's our baggage from our industrial and technology driven world. The expectation that these things exist in Costa Rica is our problem not the Tico's.
Even after living here 15 years, occasionally some interaction with the locals becomes challenging. When this occurs, I simply remind myself;
"If you don't expect much, you won't get disappointed"
Then I step back, take a second look at the situation that is beginning to frustrate me and remind myself where I'm at, who I'm dealing with and why I'm here. Then the situation at hand doesn't seem so irritating.
Foreigners who do manage to stay for a long time in Costa Rica do so because they possess patience and flexibility.
People who become frustrated here and decide to go back home don't do so because they couldn't find their favorite beverage or a suitable appliance. They leave because they couldn't adapt to the local culture.
Sometimes the unexpected trials and wide differences in cultural understanding make the transition much more difficult than expected.
Years ago I noticed several cultural differences that used to make my life in Costa Rica frustrating. The concept of time I brought along. The expectations of efficiency I had become accustomed to. Misunderstandings with the language I needed to learn.
Cultural differences in comprehending time can be attributed to the fact that Costa Ricans and foreigners place different values on time. People in traditional cultures tend to have similar attitudes towards time, and Costa Rica is still a more traditional culture. Industrialized cultures tend to think of time as money. 
Tico's live for the pleasure of 'now' and when necessary, take the time to exchange a little work for enough money to get by on.
We are continually bothered by what we foreigners view as a lack of punctuality on the part of Costa Ricans. Ticos will say, "I'll be there manana", but they usually don't show up. Often they are not hours late, but days late, with no excuse, no phone calls, no apology. Things get done here in their own time, not in the time you want to impose.
New resident's who can slow down and adjust to Tico time, have a much better chance of making a success of their new lifestyles.
Obtaining residency here usually takes much longer than expected. You need to hire a consultant to get a drivers license. The list of frustrations goes on and on. The bottom line is, if you are not able to slow down and adapt to the culture you're probably going to end up back where you came from.
Culture is embedded in languages, and misunderstandings often arise due to the way in which people of distinct cultures express and understand language content. Europeans and North Americans are very direct. In Costa Rica, the Ticos don't say things up front. It's part of their culture and is considered bad manners.
If you don't understand the culture you get frustrated and some folks become angry and this offends the Ticos. Fortunately, Ticos tend not to follow verbal aggression with physical aggression, creating in reality a live and let live culture.
Misinterpretations therefore arise because Costa Ricans view foreigners as “rude” while North Americans find Costa Ricans to be “indirect” or even “dishonest.” Many foreigners feel that they have had to learn to decode what their Costa Rican associates and friends are really trying to say. It's not that Ticos lie more, it's that they are trying to save face. They don't want to disappoint you. If they don't know the answer, they say to themselves "I don't know but I want to give my best guess." You have to learn to listen carefully and read between the lines. A simple word like "Ya" can mean "it's already done", I'm doing it right now, or I'll get to it soon"
We've all faced new challenges in Costa Rica and those of us who have been able to acclimate enjoy the benefits. The country's strong democratic tradition, innovative environmental programs, museums, cultural activities, ideal climate and affordable cost of living continue to make it a logical destination for multinational companies and retirees.
The option to live a lifestyle similar to that in a large North American city is here if you want it.
Check out the selection and pricing in any of the major shopping malls or at the local supermarkets. Most products that are imported here from another country incur duties. These duties are built into the price you pay at the cashier. If you want to live and consume the same products available from overseas, they are available here but more expensive than those produced locally.
I prefer the old days before there were shopping malls filled with international retailers and restaurants. I don't miss any of what these new franchises have to offer. I patronize typical Costa Rican businesses and my budget is much more affordable.
It's nice to have options and that's a philosophy I recommend. Plans tie you down. Options offer freedom. You don't irritate someone because you exercised an option. But there are many times when plans did not materialize as expected and someone gets irritated. Keep your options open and your plans to a minimum.
Live like the Tico's, adopt their attitude and adapt to their culture. You may live longer and happier!