Insulation doesn't care about directions, so whatever keeps a house warm in a cold climate will help keep it cool in a hot climate. Vapor barriers are different--my understanding is that the vapor barrier should go on the side of the wall that sees the most humidity. But insulation simply slows down heat transfer in all directions, so as long as you have a way to cool off the interior, whether it's AC or a cool night breeze, any insulation will hold the day's heat at bay.
Consult a local professional about the best insulation and vapor barrier choices for your area, because humidity and local pests can influence the effectiveness and longevity of your system. Make your decision based on factors such as those, because as far as heat transfer goes, an R-value is an R-value. If your energy comes from sustainable sources, the "green" insulating materials will be clear winners for sustainability, but otherwise just get the best insulation your budget allows.
This answer gives a good overview of some of the insulating materials you might consider.
If you have questions regarding the effectiveness and durability of insulating materials, the folks at Home Improvement can probably help you out.