1 pair of shoes
Baby powder or flour
Dark colored scrap fabric
Tissue or paper towels
Yarn & needles/hooks of your choice

I have these filthy old shoes. I can't bring myself to throw them away because they're very comfortable, but I can't exactly wear them in their current condition either. They used to be baby blue. (Here they are. Yeah, I know. Gross.)

You need to get an exact shape of your shoe panel so that you can knit/crochet your covering without extra fabric hanging over the edges. To do this, cover your shoe in baby powder. Put a lot of powder on so it will transfer, paying special attention to coat the edges very well. Then take a tissue and wipe the excess off the parts you didn't mean to get it on. (*This works best on cloth, not so good on shiny stuff like patent leather. Since you're covering the shoe up anyway, you won't mind ruining it by using paint instead if the powder doesn't work.)

Step 2:
Take your dark colored fabric and place it on top of the shoe, taking care not to pull it back up and move it after it has touched the powder. Press down the fabric flush against the shoe. You can tell it's transferred when the white powder starts seeping through.

Step 3:
Remove the cloth, and you will have a powdery imprint of the shape of your panel to be covered. Cut this shape out and use it as a template. Don't worry about which side is which; since your shoes are mirror images of each other, you'll make one shape for the front side and one shape for the back side.

Step 4:
Analyze your shape and plan your attack. Crocheting would be the easiest since you can just kind of "go", but if you wanted to knit these, you'd need to do some thinking. Here are 3 different options I came up with for my shape (I ended up choosing the first one):

Step 5:
Choose your yarn (I'm using my own handspun hemp) and get started. Measure your fabric, knit a gauge swatch, and use that to calculate your number of stitches on each point. I will scan in my notes page to let you see how my brain was working when I planned this out. Here are my initial measurements:

Then I combined that with the information from my gauge swatch, 3.5 stitches and 5 rows per inch, and came up with this version (green arrows represent my plan to short-row shape):

Step 6:
Sew on your shoe-cover and embellish it if you feel like it needs more stuff on it. I found some goodies (ribbon, flower pins) in the clearance bin at Joanns that I have pinned and will eventually sew onto the shoe. (My hands hurt so bad from knitting the hemp that I need to wait a few days before I can finish sewing, hence the reason there are pins all over the picture of the "done" shoe.)