Take a shuttle to get to and from the airport. They are much less expensive than regular taxis. Taxi fares are not regulated, so the prices vary greatly.
Rent a car and drive around the islands. It's the best way to see the real Hawaii. Make frequent stops.
On Oahu take TheBus, Oahu's excellent public transportation system.
On Oahu take the Waikiki Trolley which makes stops at key places.
A self-guided walking tour is a great way to explore downtown Honolulu on Oahu, Hanalei on Kauai, Lahaina on Maui or Hilo on the Big Island.
Take a hike. There are many wonderful hiking trails. You can even hike to the top of Diamond Head on Oahu.
Take Hawaiian Airlines, Island Air or go! Airlines to fly from island to island. If you plan on making several inter-island trips Aloha has a special six-flight coupon book.
A day tour to one of the islands with Polynesian Adventure Tours is well worth the money. Airfare and tour bus are included in the price.
Take a helicopter to really see some of the out-of-the-way places. You can see Kauai's beautiful Na Pali coast or fly over Kilauea volcano on the Big Island.
Take the "Expeditions" ferry from Maui to Lanai.
Consider a full week cruise on NCL (Norwegian Cruise Line.)
Many tourists just go to Hawaii and never leave Waikiki. If you do so, you are missing much of Hawaii.
Renting a car is by far the best way to see the islands. Be courteous and remember that things move at a different pace in Hawaii.
Look for discount air coupons for inter-island flights. You can save lots of money.