One of the most helpful books I ever read was about 20 years ago about "capsule" wardrobes. The idea is to pack a small number of pieces all in one of 2 colors or a combination of the 2. This way everything you take will co-ordinate and you can make tons of outfits. I have used this method for travel ever since-even if just for a weekend. On cruises I have used black/tan, white/tan, denim/camel, and black/blue. We went to visit our son in KC last weekend and I took 5 pieces that would have made about 15 different outfits if I had needed to. On a cruise the trick is to take casual and dressier pieces that will go together and don't forget a light jacket or sweater that goes with everything!