This tip comes from Jane, whose skin always looks flawless and completely natural:
The skin isn’t smooth like a piece of plastic, so to get full coverage apply your concealer with the Camouflage Brush using criss-cross motions. This gets the concealer into the fine lines on the skin that aren’t normally visible.
Then, to make your concealer completely disappear, feather the edges with your ring finger. The warmth from your finger will melt the concealer into your skin.