I put the pattern back in the envelope they were in when purchased. Nice picture on the outside with all the info needed for fabric, notions. Has the sizes, etc. Mine are sorted by size. I was lucky to find boxes at the grocery store that are the correct size for the patterns to stand upright and easy to sort through when looking for the one I want.
Now what to do with them when the kids outgrow those sizes--or the adults, too?! Some of mine are very old but with the prices of the patterns and fabric nowadays, it's cheaper to buy clothes than to make them. Clothing patterns have little value for reselling or exchange.