The Cardinal Rules Of Carry-Ons
Focus on packing only the essentials. Limit yourself to two pairs of shoes, two pairs of pants, and wear your heaviest items on the plane. Bring no more than one week’s worth of clothes. For longer trips, plan to do laundry along the way. Be efficient with your selections. Ensure that each garment you bring can color-coordinate with everything else in your travel wardrobe. Bring only items that work with multiple outfits, otherwise leave it at home. Clean your wallet/purse of old receipts and any junk you don't need, swap your paperbacks for a Kindle, and forget about those “just in case” items that you can easily buy where you're headed.
Consider using compression bags to save extra space, or roll your items as tightly as possible like I do. Stuff socks, brushes, other small items in the space between your shoes. For the ladies, tuck your brassiere, cup side out, in to the corners of your suitcase where the shape more closely matches, and then pack your rolled clothes in to the cup as normal. Check in advance if your airline enforces weight limits for carry-ons. Maximize your “personal item” by swapping a purse or laptop bag for a beach bag or backpack that can fit easily under the seat in front of you.
Embrace the simplicity and freedom of carry-on travel and you'll never go back.