For a while, I was selling gently used fashions and part of my vintage boot collection online. This involved preparing packages and taking them to the post office, often in rain or snow. My favorite for this kind of transport is a large messenger bag - my large Timbuk2 wore out after 8 years, and I'm currently in love with the Chrome Metropolis.

Since clothing and leather is susceptible to picking up odors, I'd prepare my packages and put them in a plastic bag with a dryer sheet or two before placing them in the messenger bag. This was effective in keeping my packages from smelling like onions or old books or whatever else might have been in my bag the previous day