I agree with Fishcouple, and keep in mind your customer will be paying for shipping. I would put a 5x7 piece of cardboard in the envelope to keep your items from getting damaged because you don't want to risk getting bad reviews for damages (customers tend to blame the shop owner for the errors of USPS). Also, I personally would never put a package out for the mailman, as you can't be certain who picked it up. I always go to my post office or a USPS mailbox if the package is small enough so that I know personally that my item has shipped and when. So far, I've not had anything lost in the mail and most of my reviews rave of quick shipping. That is a very important thing to most buyers.
Blessings to you,
<3 Jewel