Shipping charges within the country
If you have shipping things in USA and they weigh within the 14 ounces limit, send them through the First Class mail. This is a great service and offers good and affordable rates. Moreover, the items are also delivered on time. You can buy white poly mailers on EBay very cheaply. On the other hand, the items that weighs 14 ounces or more, for with USPS Priority Mail.
They will provide you with free of cost supplies and you can get these from USPS.com or the post office. They will also send them to your doorstep without any extra charges. Also, avoid using boxes in favour of Priority Mail Tyvek whenever possible. This is because envelopes are less heavy than boxes, and it will cost you less when shipping them.
How to package your items?
Give extra care to while packaging and keep a check on how much it weighs. This is important and over packaging becomes expensive most of the times. This will cost you more, as you use more packaging it becomes heavier. Furthermore, purchase labels and poly mailers in bulk in order to save some money. You can get these on EBay. Make sure you compare prices of these items on a regular basis. This is because you could find a discounted offer elsewhere or a special deal on certain items. Price shopping is a vital aspect when it comes to cut costs.
Do detailed research
Perform a good enough research on how to obtain free boxes or envelopes if you want to ship the package from First Class, Media Mail, International or Parcel Post. You can also save loads of cash by shipping from the official USPS website. In order to do this, log onto the internet and visit USPS.com to send items.