Before you leave, use a printable checklist of items you need to pack, and where you’ll be packing them (carry-on or checked luggage.) Include all your frequently-forgotten or last minute items: batteries, cell-phone charger, toiletries, etc, and leave blanks for the specifics about clothes, shoes, and other valuable items.
But here’s the most important part of this list: Keep a copy of the list with you. If your checked baggage gets lost, you won’t have to try to remember what it contained, and you can share the list with the airline.