Well like most countries respect for the elders goes a long way. Always respect the police over here and please never insult the government or king. This surely will get you into some trouble or expelled from the country. Also be carefull what you photograph no government buildings cars or personell or event would be save.
Other than that its a very nice relaxed place with some stunning natural attractions that is a must see. Generally if you stay calm and talk with respect to the locals you really get a long way.