The cultural differences between Europe and Central America are huge, one could write a very large book on the subject. Below you will find some useful hints that we have picked up along the way to make your stay more pleasant and enable you to get along with the local inhabitants.
Bargaining: Bargaining in Costa Rica is only customary when buying souvenirs or objects of art. In markets and shops food is bought at fixed prices.
Politeness: Politeness plays an important role in communication all over Central America. When addressing somebody, in a shop or bus, say hello first. A simple "buenos días" or "buenas tardes", accompanied by a smile, works miracles. Likewise, a greeting will gain a return greeting, then, the actual interaction begins. Upon entering a communal space, such as a restaurant or waiting room, it is also very polite to say hello to everybody present.
Clothing: Make sure you look well dressed and clean. This is an important issue to the people of Central America. Even poor people do their utmost to look well kept. As you seem to have the money to travel all the way from Europe to Central America, you are bound to be a rich person in the locals’ eyes. You will gain respect if you dress properly. Of course, this does not imply you have to wear your best Armani outfit when wandering the streets. Best leave jewels and valuables at home. Do not put on revealing clothes, as it is not always appreciated. Shorts are allowed, for men and women, but only on beaches and in some coastal resorts. Bathing clothes are only allowed in swimming pools and on beaches. Many local women wear a T-shirt on top of their bathing suit (in order to avoid male attention). Dress properly when visiting churches, out of respect for the locals and their culture.
Macho behaviour: The myth that characterizes men as being strong and women as fragile and dependent has not been dispelled in Central America. Macho attitude and male pride are widely evident. Here men still whistle to attract the attention of a woman.
Solo women travellers tend to receive plenty of (unwanted) attention. If you do not like this, it is best to ignore them. Minimise the problem by dressing conservatively. Carrying a wedding ring may help. Avoid dark places and lonely beaches if you travel by yourself. Of course, there are more than sufficient ‘normal’ men around.
In general: Be constantly aware of the fact that you are a guest in a country, which has a different etiquette. They do not behave differently, you do.