Build around one colour family
Choose a base — navy, black or tan — and pack only pieces that work with it. Five tops and three bottoms in one family give you fifteen outfits. Five tops and three bottoms in random colours give you five.
Wear the bulk
Your heaviest shoes, your jacket and your thickest layer travel on your body, not in the bag. That single habit frees roughly a third of your case.
Wash, don't over-pack
A small bottle of travel wash and a sink give you unlimited clean clothes. Pack for four days regardless of trip length and everything else takes care of itself.
Keep a permanently packed kit
Toiletries, chargers, adapters and medication live in a bag that never gets unpacked. Restock it when you get home, not the night before you leave.