Packing items can be a tough process for some people simply because they don't know how to make a box. Yes, many of us are geometry illiterate, but making a box can be a simple or painful process. There's some key things you'll need before you make a box/pack it. Also, be prepared to do and go to places you may not have done before. Some things like cardboard boxes, and where they can be gatherered will be answered later:

How to Make a Box
Start by gathering materials you'll need in order to make a box. Also, clear out a work station so that you can clean up later if due necessary. Anyhow, gather the following materials: Shipping Tape, Adjustable Razor Blade, Pencil, Scissors, Ruler, and the item. These are key items to make a box correctly and so that it fits with proportion.

Next, take the slab of cardboard, and start marking lines on it so that you can make flaps, folds, and border lines. Take the ruler, measure the item. For example, we're using a complete TMNT NES game. The dimensions are 7" (length) x 5" (width) x 1" (height). So when you make the box, adjust some extra space for packing, and the dimensions for our box is going to be 8" x 6" x 1.5". The idea is to leave enough space for the item to get stuffed around, while not edging it so close that the item has to be squished. Use the ruler, and dot the lines much like the box on the left. After that, using the razor blade, cut the cardboard out of the slab based on your markings.

Use the scissors to cut part of the flaps out like above. Also use the technique of making a partial cut to make the folds. Basically, take the razor blade and slightly mark lines on the cardboard. Then, take the reverse side of the razor blade, and run it along the lines to make a crease. And from that step on, your box is practically finished. Just fold it up, and tape it on a few corners, and voila. You just saved yourself anywhere from $.50 to a $1.00 by not buying a box.

Stuffing the Box
Packing your box can be a pesky process if you aren't prepared. The amount and type of packaging materials usually depends on what you're shipping. If something precious is being shipped, like a bottle or ceramic statue, then you might as well you lots of stuffing so the box doesn't even make a rattle in your direction. If you're sending something structured like a video game or trading cards, less stuffing is needed. In most cases, I recommend stuffing boxes with newspapers, shredded paper, styrofoam packing, sponges, thin plastic bags, and cardboard slabs. The best one in my opinion is newspapers, since they're cheap, and you have no other use for them besides the garbage. Newspapers are somewhat heavy, so the item will gain weight. Styrofoam packing is the most efficient, but also the most costy and rare. Thin plastic bags work very well, and are quite common. Avoid any thick papers like color-coated magazines, we don't want anything too heavy. Use sponge foam in extreme cases when it involves glass ornaments and other things.

Where do I find cardboard?
Cardboard can be found nearly anywhere, it just comes down to dedication and if you're willing to get it. The easiest, cheapest, and most efficient way of getting cardboard boxes is from garbage dumps. No, not the landfills, I'm talking about the garbage rims behind commercial stores and outlets. Many stores have no uses for cardboard boxes after they receive items, and will quite often throw their empty cardboard boxes in their garbage dumpster. I'm not saying that you should go out and just start digging through garbage dumpters. Just go behind your local Best Buy, and you'll find the cardboard overfilling the dumpster. Grab a few and drive away. You can also ask store managers what they do with their boxes. Some stores will be more than willing to give you their cardboard boxes since it costs stores more money to shred them up. Some stores will also have signs like free boxes, but many stores require that you ask for them.

If you don't want to get your hands dirty, than simply go to a store. Wal-Mart usually sells small boxes, but for expensive prices. You're better off going to a local outlet and just taking them, but it's up to you.