Mistakes: Applying too much concealer, using a too-thick concealer and using the wrong shade.
The best technique: Only use the concealer where you really need it, such as under the eyes and around the nose. Thick concealer will gather in any fine lines and crease
N.b. It is also worth having a separate concealer for spots as you will want a little bit more coverage on problem areas.
Blend, don't drag
Remember that your concealer should never be more than one or two shades lighter than your skin tone!
Use your ring finger and lightly pat in the product, as the warmth of your fingers blends the concealer a lot better than a brush or a sponge.
Never drag concealer under the eyes, as this moves the product around and does not blend it into the skin.