Pack any liquids (shampoo, body wash, whatever) in clear ziploc bags in case of spills. We had a shampoo blowout on our last trip, but the mess was contained to the baggie and my toothbrush didn't taste like soap! Also, bring one of those mesh shower puffs instead of a cloth - they dry faster and use less soap. That's if you're using a liquid soap.
Another tip (maybe better in packing tips?) - pack your undies in clear ziplocs so when they search your bags - and they will - the customs folks can see what's inside without littering your unmentionables all over the airport.