I do a lot of sewing and make a lot of crafts and as a result I have a lot of money sitting in patterns. As I tend to choose a basic pattern and adapt it to suit whatever I'm making, I like to trace my patterns onto cardboard (if it's a craft pattern) or lightweight interfacing (for dressmaking) for longevity.
As most of my craft patterns are for small items empty cereal boxes do the job perfectly. Just slit the sides and open them out flat then draw the pattern onto the inside. Cut them out, label the pieces and they are easy to work with and long lasting.
For dressmaking patterns, tracing off the tissue paper pattern onto interfacing keeps the original intact for future use. This is particularly useful for the multi-size patterns. The interfacing makes cutting the pattern off the fabric a breeze as it stays put when it's laid out, helping with cutting accuracy.