From the New York Times: How to pack for a 10-day trip in one standard carry-on bag:
Folded clothing takes up too much space. Instead, Ms. Poole tightly rolls everything, which also minimizes wrinkling. This suitcase will hold three pairs of shorts, three pairs of dress pants, one skirt, three pairs of casual pants or jeans, three nightgowns, three bathing suits, one sarong, three lightweight sweaters, four dresses, 10 casual shirts, six dress shirts, a clutch, toiletries and two pairs of shoes. She’ll wear the third pair of shoes, as well as jeans and a longer sweater.