Dusk is the time when the mosquitos come out in force, especially the malaria carrying ones, so make sure than you have applied plenty of mosquito repellent, and preferably wear long trousers and a long sleeved shirt.
Riverside settings are of course very good places to capture sunsets, partly as you are not enclosed with tall vegetation all around you, and partly because of the beautiful refplections you get on the water.
Ok, this is the last sunset picture - for this time. The colours of sunset pictures are often enhanced if you underexpose your shots by one or two stops. Try it and see.
I make no appologies for including several sunset pictures as part of Nightlife tips here - I am an absolute sucker for sunrise and sunset photos and will take them whenever I can.
The sun would set between 17.30 and 18.00 each evening, and as is the norm in the tropics, it is over rather quickly, so make sure you have your camera ready!