The application of concealer is the most important step in any makeup routine. Concealer is the product that can brighten and lift the face. Concealer should be smooth to the touch. A formula that is too dry is bad for the delicate skin around the eyes. You should choose a different texture of concealer depending of your skin condition. Concealer should be the same shade as your foundation or a shade lighter. For extremely dark circle choose a heavy formula concealer in shade that is lighter than your skin. The big mistake is using too light or too white shade. If you are using a concealer in the same colour like foundation you can use it before or after foundation.
Before applying concealer you should prepare the area under eyes by applying eye cream. You should remember about applying eye cream if your skin is very dry. If you have oil skin be careful with eye cream because your concealer can move around the eye area.
Apply (best option is using a concealer brush or your fingers) beginning at the inner corners of the eyes, close to the lashes, where there is darkness. Gently blend by pressing your fingers. Make sure there is enough to block the darkness. After application concealer and foundation remember to use a powder, your concealer will be long-lasting and you will avoid a mess under your eyes when you apply mascara. Instead of concealer you can also use a stick foundation one or two shades lighter.
Corrector is a great choice for covering very dark circle, red spots, hyperpigmentation.
Diorskin Nude Concealer
Colours: ivory ,beige, honey
This concealer is very creamy, very lightweight texture. Offers great coverage but very natural results. Blends very well, perfect for pigmentation or red areas.

MAC Studio finish SPF15
Colours: available 15 shades
Definitely one of my favourite product.
It is very creamy, long-wearing, great finish with medium coverage (be careful under eyes area). Blends very well, I use a concealer brush, it is great for dark spots, redness.

YSL Touche Eclat
Colours: available 7 shades
It is great for delicate area around the eyes. It is very light and easy to blend but did not to cover dark circle as good as it should be. To be honest it is not my favourite product, it is more like very posh and gold looking gadget.

Yaby concealer
Colours: 24 shades
Creamy texture, easy to apply, very pigmented to correct any imperfections. Great to be use on the face and body. Great for around eyes area.

Kryolan Dermacolour Concealer Wheel
It is very pigmented, thick, heavy. Provide full coverage, best for tattoo, scars, skin pigments. The most effective and long- lasting. There is a huge selection of colours. It is good for professional use. It is perfect for runways, photo-shoots.

Max Factor Pan Stik
Great for larger areas of pigmentation, amazing coverage without being cakey, easy to apply.
Can be used as a concealer.