Print labels online. Drop in box.Working nights means I have to be at the PO when they open or it doesn't ship. There is always a line first thing in the morning. That's the last place I want to be after working all night.
If you can use ODT... you are quite capable of printing your labels online.
Doesn't get any easier than that.
Having an appropriate box is the hardest part.
As for smaller items; I always price in a bubble mailer in to my shipping costs.