Paint the bottom half of your nail and let it dry completely. This is important, because the stickers you are using later will destroy all your hard work if you are too quick. One way to check this is to lick your nail. Seriously! This will not ruing your mani if the polish is not dry and you can actually taste the difference between wet and dry polish.
Use reinforcement labels (the round stickers you use to protect holes in your papers) to divide your nails in half.
Finish with at least two layers of your second color. Peel of gently before the polish dries.