Pack one week in advance- this is a great tip I've picked up in my 20 years of travelling. The general rule of packing is pack what you think you need and then halve it, it works everytime. If I was travelling alone for 10 days I would only need 1 small backpack. Experienced travellers only travel with one cabin bag & that is it!
If you pack the week before, and only take away, not add items, you should end up with a nice lightweight "essentials" pile. The night before your trip place your pile on your bed then slowly pack your case. Each time you pick up an item ask yourself "do I really need this for the trip". If all else fails you can probably buy it over there. Don't fall into the "just incase" trap, because trust me you wont use it.
My personal goal for this trip was 1 big suitcase, 1 backpack as a cabin bag, 1 backpack travel stroller and my small saddle bag handbag for two adults to carry. Keep in mind that airlines are very strict nowdays on weight limits. For us we were allowed 23kg each suitcase plus 2 x 7kg cabin bags and 1 stroller allowance (which we didn't need). Please always check with your airline before you fly.