In the New York Times, Shivani Vora and Michelle Higgins write about packing efficiently and effectively for any trip:

Do the clothing countdown: If you need a mantra to help streamline your wardrobe, use the 5, 4, 3, 2, 1 rule for a weeklong trip: Limit yourself to no more than five sets of socks and underwear, four tops, three bottoms, two pairs of shoes and one hat. The list should be adjusted to suit your needs. Throw in a swimsuit and exercise gear or a suit jacket and dress if you’ll need them.

Also, “Roll your clothes. This helps to maximize space and minimize wrinkles.”