First grab a shoe an start applying the black paint.
Once the shoe is covered, add in some blue spots (they really don't need to be perfect) You can mix in some white to make the blue lighter.
Once you've got the blue on you can mix in some purple (mix the blue and red) in the areas you would like
When you've got the shoe looking how you want it, put a bit of white paint into a spray bottle. then add in a bit of water (2 thirds paint 1 third water) and spray the shoes to create the stars. Honestly no matter how bad it looks, adding the stars really helps
Use a small paintbrush and a toothpick to make some larger stars
Then scrape off the paint that got on the rubber parts wih a paper towel or a toothpick
Spray them with some sealant the you're finnished!