Small shops may be a better source. Hospitals also have sturdy boxes, often in a variety of sizes. Large offices may have paper boxes with covers. It is worth a few phone calls if finances are tight and you don't want to spend money on the boxes. The easiest and quickest way to get moving boxes is to buy them from a moving company.
Many companies sell used boxes at a reduced price.
They are flattened, so they are easy to transport home, and are of a uniform size and shape, which makes packing the truck easier. Some companies will buy back boxes if they are still in good shape, so some of the mover's cost can be recovered. You will also need packing tape, a large permanent marker, paper plates, and plain white paper towels. I begin by packing purely decorative items first, because I know I will not need to use them right away. I have a lot of collectibles and pieces of art, so this is a large part of my packing.