To keep your earrings from escaping, I include a set of "rubber ear nuts" with each pair. Ear nuts are those doo-hickies you put on the back of your earrings to keep them in place. They are always seen on the back of "post" style earrings but not on "wire" style earrings, as I usually sell. When folks buy my earrings they usually assume the ear nuts are there just to keep the earrings on the display card and the ear nuts get tossed in the trash. This is what rubber ear nuts look like.
I like them because you can slide them just as far as you like, up and around that curve on an ear wire. I personally use them on my post earrings because they don't pinch the back of my ear. And if I misplace one, most stores with jewelry have little packages of them for sale.