I used my Tulip Fabric Markers again, and the steps are after the break!
Sorry for the crappy line quality, I used the marker after I had finished the shoes and it was a tiny bit dry by that time (and actually I hadn't finished the shoes yet). So once that was done, I filled in the little parallelograms, one color at a time. I did them in a pattern of blue, purple, green, pink, and yellow. You don't have to, but it just helped me give them a certain amount of consistency.
You're going to look at the pictures below and think "Those are not the shoes in the top picture", and no, they aren't...yet. Once all the colors are done, you can see that they aren't nearly as bright as they are in the end, and the solution is to go over the colors until they're as strong as you want them to be:
And now you're thinking "You lied to me again, sir. Those are not the shoes. Again." (I use sir as an insult when I'm driving, and sometimes to people when I don't want to be rude. It's all in the tone!) BUT THERE IS ONE LAST MAGICAL STEP. Now you're going to go over all of the black lines again, either with your black marker if it's still kickin', or with a black Sharpie if you're me and your marker died a sad but useful death. This last touch defines the shapes and really brings out the colors, and also covers up any potential mistakes you might have made!
And there you go: awesome shoes on a budget.