For a week of travel, pack two pairs of bottoms, three tops, and one nicer outfit into your carry-on. Also pack one pair of socks and undergarments for each day of travel. This will create seven outfit combinations. Don't forget pajamas, if you use them

Check the weather for your location before packing, and always plan for extreme weather conditions. Choose clothing and shoes based on your planned activities

For example, you may need a swimsuit, hiking boots, or a warm hat and gloves

Different occasions will call for different types of dress. Business trips will call for more professional clothing/shoes while a camping trip will call for comfort and warmth

Pick items that can serve multiple purposes and fit multiple outfits

For example, some pants will work both as pyjamas and bottoms of an outfit. A neutral colored classic shirt can also be both dressed up and dressed down to serve multiple occasions

Since shoes take up a lot of space, consolidate what you bring. Pack one pair that can be worn with a nice outfit and one pair that can be worn for comfort

If you are planning on going to a beach or pool, bring shoes that can get wet (flip-flops or sandals, for example)