As kids, whenever we went on holidays anywhere, it was drilled into us to check under our beds, in drawers and closets before we checked out of a place. The same principle applies here. While your removalists or friends are packing your stuff into the truck, you need to constantly check that everything has been packed from each room.
When everything has been taken out of the house you need to do one final check. You can’t be slapdash about this— doing it thoroughly is the only way to go. Remember that you might not get another chance to look for anything that you have left behind. Even if you are only moving out of home to a flat a couple of suburbs away, you will save yourself some time and hassle if you can move out all at once and not leave anything behind.
I’m sure your mum and dad would love the visit—but I know that if I left anything behind it would be gone by the time I was out the door, thanks to my little brother and sister. It might be a good idea to write up a list the night before of the things you should check just before you walk out the door for the last time—cupboards, drawers ,lights, power points, hot water service off (but not if you’re moving out of your parents’ place!), windows and doors locked.