The laundries onboard ship are good and the prices are reasonable EXCEPT for things like socks and underwear. Fortunately, those sorts of things don't take up much space and can be stuffed into shoes or corners of suitcases.
Some people take their oldest, rattiest underwear and throw it out as they go along. Not too romantic, if you're into romance.
Sleep naked. It's fun and you don't have to pack nightclothes.
I can't remember who came up with this hint, but it's a goodie. Ladies can get an extra day out of a pair of panties with panty liners.
Try to figure out an evening wardrobe for ladies that revolves around a pair of black silk slacks. Also, the "LBD" (Little Black Dress) can make a number of appearances with different accessories.
The polo shirt men wear on casual nights (or informal with blazer) can be worn again the next day. It's called the "air and wear" theory of dressing.
pamda -- CM First-Time Cruisers Editor