Use clear nail enamel to give your nails a “finished” look.  It dries quickly, helps strengthen your nails, and hides mistakes.  You can then apply color when ready.

To clean up any color that got slopped around your nails (fingers or toes), use a pumice stone in the shower on the skin surrounding your nails.

Keep your manicure fresh by applying a clear top coat every other day, which evens out the finish and gives a high gloss.  If you need to do touch-ups where the color is chipped along the edge, dab on a bit of polish and wait for it to dry a little.  Then put clear top coat over the whole nail.  It helps to blend in the repair.