Apply a clear base coat. I used Sally Hansen Complete Care Extra Moisturizing 4-in-1 Treatment. It really does strengthen my nails and keep them from staining.
Start by separating 10 pieces of sellotape. Stick them in a triangle form at the top of the nail. I stuck mine from the corners of the nail tip to the middle of the nail. This is the only tricky part, it just takes a bit of fiddling.
Check that the tip of the triangle is in the center of the nail. Cut the sides of the tape shorter so they don't stick to the other nails.
Apply two coats of red nail polish. Don't paint the colour on too thick or it will form ridges at the sides when you pull the tape off. Wait for the colour to dry completely before removing the sellotape.
Apply a clear top coat. And you're done.