Lay everything out on a bed before packing it. Put similar things together: chargers, shirts, toiletries, camera accessories. Duplicates become obvious when they are beside one another.
Start the edit with the trip you have booked. Check the weather, luggage allowance and whether laundry is available. Clothes that can be washed and dried during the stay may save more space than a new set of packing cubes. Keep the layers and equipment the actual conditions require.
Try the camera bag on for a short walk. If you already want to leave a lens behind, decide what you would miss without it. Take the battery and storage you need, but check whether every extra accessory has a specific use on this journey.
Give documents, medication and items you need in transit an accessible place. Check the relevant carrier and destination rules for restricted items. Pack liquids so a leaking bottle cannot reach paper or electronics, and leave enough spare space to put a jacket away.
Close the bag without sitting on it. Carry it up a flight of stairs if you can do so comfortably. This tells you more about the arrangement than the total weight alone.
After the trip, leave your unused items out while unpacking and make a short note. Separate genuine essentials that happened not to be needed from things you brought out of habit. Use that note next time.
