Many chain drugstores will allow you to exchange a mistake. To increase the odds in your favor, take a careful look at your natural lip color, says makeup artist Cynde Watson. Go only a couple of shades brighter or darker.
As a rule of thumb, if your lips are thin, avoid dark shades, since they make lips look narrower—a natural shade of gloss will make your mouth look fuller. Conversely, if your lips are very full, be judicious with the shine. Stuck with a color that seems too intense? Use a lip brush to mix it with a clear gloss.