My number one recommendation for travel clothes is Uniqlo. I love their Airism shirts for warm climate destinations. Basically anything light, layer-able, and high wrinkle tolerance is great for the bag. Pictured here is 9 days of clothing in a carry on for two destinations: one hot climate (Lima) and one rainy/cool climate (Cusco). Hint: shoves socks in shoes and roll clothes up for more space.
I learned my lesson on overpacking after dragging a huge suitcase around Europe with me for 7 weeks. This carry on bag is MUCH more reasonable