Keep your hands very clean.
Before you do anything, it's important to make sure your nails and the skin around them are thoroughly dirt-free. Then remove all traces of your last color with an acetone-free remover (anything else unnecessarily dries out your nail).
Always keep a nail file on hand.
If you're someone whose work or gym routine causes a lot of wear and tear, Dr. Prystowsky suggests keeping a nail file handy to smooth away any rough edges that happen on the spot. Work in one direction with the grain of your nail for a smoother finish.
Protect your nails with a base coat
Painting your nails at home is no excuse to cut corners by skipping the base coat. Dr. Prystowsky points out that this step not only protects the nail from being stained by the polish, but also helps the color look more saturated and opaque with just one coat. And if you really want to take things to the next level, Dr. Shamban suggests adding a coat of clear gloss between each layer to add extra shine and protection.