If you plan a trip to a destination with high humidity, save the silica gel packets that come in purses or shoes. Or you can ask for them at your local camera store. When you pack them in a plastic bag with your medications, binoculars, camera or iPod they prevent the humidity from damaging or fogging them.
When you get home, put the gel packets in a 150 degree oven for about half an hour and you can reuse them your next trip.
For your clothes, pack a large garbage bag inside your suitcase or duffel bag and pack your clothes inside it. Everything will stay drier.