If your nail polish collection is getting stale and sad, you can perk it up by mixing two polishes together for a new shade. Look at your polishes with an artist's eye and select two colors that have harmonious potential. Avoid combining two dark shades -- one will dominate and the results will be minimal. Instead, choose a light shade and a dark shade. You might take inspiration from manicurist Marina Sandoval. She mixed a pale pink with beige to create the ultra-nude shade worn by Kate Middleton on her royal wedding day.
Set up your work area by taping a 12-inch sheet of wax paper on a table. Use the scissors to cut a paper funnel from one corner of the envelope. Snip a very small hole for the funnel end, just enough for a small stream of polish to move through.
Select an area of wax paper to use for shade testing. Pour a drop or two of the lighter shade onto the paper. Add a drop of the darker shade on top. Mix with the toothpick. Create a few samples, taking note of light-to-dark ratios, until you have a shade you like. Write down your recipe; for example: "Two parts dark to one part light."
Pour an appropriate amount of the lighter polish into the small plastic or glass container. Add the darker shade to match the color obtained in your sample swatch. Mix until the polish is uniform. Test the polish on one of your fingernails and let it dry to make sure you like it.
Place the small funnel end of the envelope corner into the bottle opening. Transfer the rest of the polish into the bottle, gently shaking or tapping the funnel to avoid clogging. Cap the bottle and shake well before each use. Don't forget to give your shade a new name.