If you're in the US, find a government documents depository library in your area. Most larger libraries at least should have a government documents section. Among other the things it does, the CIA prepares background information, country studies, and information that can be useful for travelers. The State Department also has information for travelers. Things to research: culture, economics, social conditions, political conditions, and health/medical concerns. Do not forget to research how the population reacts to tourists and how popular (or not) Americans are there.