Air Brushing / Photo Touch-Up

Air brushing is a technique used to 'touchup' people's faces and hair to make them look better. This can mean removing skin imperfections or adding/ improving make-up. It is often used by advertisers to make their models look as attractive as possible. It is also useful when trying to alter certain features, such as hair colour.
Firstly, you duplicate the layer.
You then use the cloning tool to remove any skin imperfections such as spots.
Then you can use the 'Gaussian Blur' tool under Filter---Blur and put it to around 2.6, but before the image becomes too blurred.
You then use the eraser tool to remove the blur on the duplicated layer on features that may look too blurred such as the eyes, lips and jewellery.
You then change the opacity to 60-70.

Changing Eye Colour
To change a person's eye colour you select the brush tool and make the size match the size of the eyes as closely as possible. Then select the desired eye colour.
Click once over the eyes, then change the colour effects to either 'soft light', 'hue' or 'overlay'- whichever works best.
Afterwards you can use the eraser tool to tidy up any smudges. You can change the opacity to make the colour look as realistic as possible.
This technique can also be used to change hair colour on a new layer.