that's an easy one. go to the windward side. find a nice cliff (preferably with some grass or beach at the bottom and somewhere to land on top) if you have flown before and know how to fly already, just toss off into the wind and you should have a ton of lift along the edge of the cliff. you need a spot where the wind blows into the face of the cliff. this will give you lift along the edge of the cliff. you can fly till the batteries die! check out the slope soaring section here, and i am sure the guys there will give you tons of useful info. what plane are you flying? even the thermal type gliders will do ok, just don't try it the first time out when the trades are howling.

I lived down near poipu for a while when i was a kid. I am jealous. you have tons of great slope soaring sites there and ideal conditions. I live in NC now, and there isn't a good cliff around for 1000 miles! my slope soarers stay in the closet.