When driving around Maui, look in your rear view mirror occasionally and if you are holding up traffic, show some "Aloha" and pull over to let others pass and the Locals will wave to you with two fingers instead of one.
Wear sunscreen always (even when cloudy) and rubber slippers (aka flip flops). Don't get matching aloha wear, whatever you do. Don't try to speak pidgin (local slang). Don't feed any animals or fish anywhere, ever. Remember to take nothing and leave nothing.
There is crime in paradise, so don't keep valuables in your car or trunk (there are trunk buttons inside the car). Don't leave your wallet on the beach when you swim, and play it smart.
Please note, when you are walking around, you may run into Activity Sales people. They only sell certain activities, from which they receive sales commissions from. They don't represent all the different Maui companies. Their recommendations are generally based on the highest commission rate, not what is always in your best interest.