I hoard patterns. Probably more than I hoard fabric. So, I have milk crates with hanging file folders to hold my patterns. Each pattern has its own folder. Each folder hangs in one of 6 (embarrassing) milk crates, separated by pattern type. (All dress and adult woman patterns in one, all baby patterns in one, all apron and costume patterns in one, all bag and misc. patterns in one, all little kid patterns in one, and all my patterns out of books in one.) I put them in alphabetical order according to the pattern maker and then within the pattern maker name, I put them in numerical order.
When I trace a pattern and cut it out in butcher paper, I will then fold the butcher paper up and put it in the folder with the pattern.
If I have the same pattern in multiple sizes, they go in the folder together.