I'm OCD, so I take my notebook. Just a simple 1" 3 ring binder that is right now bursting at the seams that I keep in a tote bag. Each pattern is in a sleeve protector, and I try and keep like-patterns together. I also go through constantly and put in new patterns while taking out ones I printed that I have decided I won't use soon. I also keep a pen and my working spiral notebook that I use to keep track of what I'm project I'm doing, as well as what row I'm on, when I started it, the pattern name, etc. Like I said, OCD.
But I love the idea of the 3x5s. I use that for a lot of recipes that I find, but never thought of using it for knitting. Thank you!