Send items such as dvds, books and cds via media mail. Media mail is a lot cheaper than other shipping methods even if the items you are sending are heavy. However, take note that media mail may take longer than first class mail so this is not advisable for shipments that you want to be delivered quickly.
Use a bubble envelope when shipping a lighter item. If your package is under 13 ounces, you can send it thru first class mail. If it is over 13 ounces it must go parcel post or priority, both of which cost more.
Use light packing materials such as plastic bags, newspaper or packing peanuts. It is also a good way to recycle by reusing these materials.
Take advantage of the post office’s pre-printed priority mail boxes especially if you are shipping via priority mail. These boxes are free so that will save you on packing materials. Second, these boxes already have prices set on them (pre-set), so whatever you put in a certain size box, no matter what the weight, will be a set cost. If you put these same items in your own box it will cost more money because it will be priced based on weight.
Ask the post office for extra priority mail boxes to bring home. This way you will have a ready supply and can pack items in pre-printed boxes at home, instead of having to do it when you get to the post office.