If you are selling on Etsy, the easiest and cheapest way to mail your packages is directly through Etsy’s platform.
So far, this is the best way I have found for 2 reasons…
1. Shipping on Etsy is cheaper. Being an Etsy seller qualifies you for commercial base shipping prices, which are slightly cheaper than the prices you would pay if you went to the post office and paid there.
2. The tracking number is automatically sent for you. You no longer have to copy the tracking number from your receipt to send to your buyer. When you buy through Etsy, their system automatically sends them an email with the tracking number + shipping information. Automation for the win!