Row One (left to right): Pink Lingerie (Revlon Top Speed), Presto Pink (Sally Hansen Insta-Dri), Hot Pink Migi Nail Art Pen (neon set). Row Two: Magenta Migi Nail Art Pen (neon set), Midnight Plum (Avon), Deep Purple Migi Nail Art Pen (neon set), Secret Peri-Wink-Le (China Glaze), Ogre the Top Blue (OPI), Blue Away (Sally Hansen Insta Dri). Row Three: Chillax (Sally Girl).
Start by taking a small plastic bag (sandwich or freezer bag) and painting nail polish on to it. Let this dry for a couple of minutes and apply another coat (keep adding coats until the polish is opaque). Do this first so that it will have time to dry. I recommend about an hour drying time on this.
While the polish is drying on the bag, prep your nails. Start with a good base coat (I like China Glaze Strong Adhesion Base Coat), then follow with at least two coats of your base colour (I used the famous, "For Audrey" from China Glaze).
Once your polish on the bag is dry enough to peel off, either gently cut (with an exacto-knife) triangle shapes into the polish or peel it off and use scissors to cut it.
Then, press the triangles onto your nail in a cool design, like below. Finish with a top-coat, and you're done.