First of all.....
Never,Never,Never ship your games USPS parcel post if the recipient is expecting the games to be delivered within three to four days.
ALWAYS,ALWAYS,ALWAYS ship parcels with a delivery confirmation. The Delivery Confirmation will protect you if there happens to be some dispute over a delay while in transit or non receipt of the parcel.
If you are shipping outside of the US and the game has a large currency value,you ship EMS which will provide you with a tracking # and 3-5 day delivery time.
The packing materials you should use are bubblewrap,a sturdy or oversized box,packing peanuts or news paper. You surround the game with bubblewrap ,line the base of the box with a peanuts or paper cushion,place the game on the cusion and then surround it with peanuts or paper . Try to make sure you provide as much of a cushion at the top as you do the base taking into account that your parcel with be stacked with many others.
-BB