So, I printed out some of Olivia's spell cards and realized that a great way to organize them is to use binder sheets that are meant to archive playing cards. I got a pack of 10 sheets (which hold 9 cards each) for like 3 dollars. Here is the result:
The only drawback is that I had to make the cards small enough to fit in the pouches, so there's less room to write. But I think these will be good for writing down quick, simple spells.