I have a Born Pretty Store review today! I'm slightly disappointed, but in myself. I didn't choose the best foil to review. I thought from the photo that it was going to be silver, but it ended up being clear and holographic rainbow-ish. Don't get me wrong, it looked pretty cool and applied fine, but it was incredibly hard to photograph. It doesn't look nearly as cool in the photographs I took. I'll have to pick a better one next time.
So if you click the link I chose foil #10. I put it over OPI: Casino Royale. You just place it on there after the polish is mostly dry but still a little tacky. I didn't put top coat on these. I've heard to put a normal drying top coat over foils, so I tried my pinky first and it lost a lot of the holographic effect. I still recommend trying foils though, just a more metallic one. This might look cool over black, but would still probably be hard to photograph.