Next time you're lipstick-shopping, apply the lipstick to the inner pad of your finger and walk outside to see the colour in natural light.  It saves getting home and realising it's a terrible shade.  (Or better still:  apply a hygienically-cleansed lipstick to your lips with a Q-Tip, and look in a mirror outside.)  Why the finger pad?  Because the skin's closest in colour to your lips themselves.