Packing is one of the most essential - if not the most essential - tasks when it comes to moving. The whole point of packing is to collect all your belongings so that you can bring them to your new home. Not doing it properly simply defeats this very basic purpose.
 
Efficient packing starts with organizing and creating an inventory of your things. You need to know which of your current stuff you'll be taking along, so that when your things get to your destination, you'll have an easier time tracking items down.
 
You also need to pack per room, so that you don't mix up everything. This is so unpacking will go faster, since you already have the boxes filled with the items and belongings that should be placed in a particular room. When packing breakables in particular, be sure to use a lot of shock absorbing material like bubble wrap and packing peanuts.
 
It's also very important that you label your boxes accordingly so that you and whoever else is handling your packages will know what's inside and which box goes where when you start unloading them into your new place. Boxes that contain fragile items in particular need to be labeled conspicuously in all sides. Also indicate which side of the box should be on top.