Here are some tips to use if you are planning on moving.
First, you should use certified moving boxes. They will, overall, save you money and protect your valuable items. The importance of certified moving boxes is that they are cardboard boxes that are designed specifically for use when moving and storing items. When packed properly, they will not crush when you stack box on top of box.
Second, completely fill your moving boxes. This includes filling in any gaps. The best things to use are crumpled newspaper or packing paper (a thicker paper that will not leave ink on you and your items, like newspaper can). All boxes are stronger if they are completely filled. Even when using certified moving boxes, if they are not completely filled, you will run the (eventual) risk of them compressing, especially if they are stacked on top of other boxes in storage.
Third, pack most of your items in small moving boxes. You should only use the larger boxes for light items like pillows, bedding and other light belongings. If you were to pack heavier items in the large boxes, they would become too heavy and it would be unsafe to move or store your belongings.