Just as you arranged the stacks of notes in some kind of order, the next step is to arrange all of the notes in each stack in some kind of order.
This can be a little trickier because it’s not always clear. The nice thing about using note cards is that it’s easy to re-order them in case you’ve discovered a better way later.
Once you’ve ordered the notes, be sure to put a number in the upper right corner. That’ll help you keep track of which note you used.