Start with the weather, your planned activities and any transport requirements. A short list helps distinguish useful items from things packed out of habit.
Build around combinations
Choose clothing that works in more than one outfit and consider what can be worn during the journey. Leave enough room to find items without emptying the whole bag.
Check travel rules directly
Airlines and transport operators set their own baggage limits. Confirm the current allowance with your operator, including handles and wheels where its rules require them.
Keep essential documents and items you may need in transit accessible. The right packing approach depends on the trip, rather than a universal number of items.