― Having trouble with dark polish discoloring your nails? ∙ 1.Always apply a base coat to prevent this problem. Also, applying a top coat will ensure that your polish lasts for days and days. ∙ 2. Before you purchase nail files, check with your nail technician to see what number grit you should use. Higher numbers are finer grit, perfect for natural nails; lower numbers are coarser, and best for artificial nails. ∙ 3. Manicure tools should be sterilized between uses. You [...].