Light clothings. Good shoes and slippers.
Bring along your Doxycycline, the anti-malaria pills. The area is malaria-infected. So, better be safe than sorry.
A lot of photographing opportunities. Bring along your telephoto lens too. Lotsa films / memory cards too.
Beach wear with a sarong or big towel so that you can "cover" yourself (especially for females). East Timorese are very conservative, so, please respect them by not "revealing" too much.
Insect repellent is definitely a MUST as the mossies there are really terrible. If you can find, bring some mosquitoes coils too. Else, you will regret.
Bring your sunblock too during the hot season.
