Have an old (in my case) iPod case. I painted mine with white acrylic paint, but it's totally unnecessary, I was going to do something else, then remembered- glitter is everything.
Take a bowl and line it with tinfoil. This will make clean up SO much easier.
Pour out a blob of mod Podge.
Add glitter and mix with a sponge brush.
And paint your case. Do a layer, and let it sit for a couple hours. Then do another layer.
Make sure to let it dry at least a couple hours in between each coat of glitter.
I did my cell phone case too.
So do at least a couple coats of glitter. Wait at least a few hours between coats. You can do another coat of just mod Podge to seal it, but you don't really need to.
Random pic I took of the phone case in the sun.
My iPod case. •the heart is nail polish- Essie's Lots of Lux• And you can pretty much glitter anything the same way. I have a handful of random things that are covered in glitter.