There is one road and look for the signs to the parks. Hire a local guide for other information that is not in books or maps.
Patience. Being in a tourist area, you will have to wait for people to get out of the water and off of the rocks.
A waterfall that is along the road. Parking on the road to Hana is a pain but worth the hiking around. I am told spring is the best time due to an increase in rainfall. Look for the small signs to little parks.