Most of you will have used the dodge and burn tools in Photoshop and will have found them
to be very beneficial to a lot of images. One problem with the dodge and burn tools though is that it's destructive
(it changes your pixel data) and we usually don't want this, so in this tip I'll show you a way around this problem.
First thing we are going to do is create a new layer by going to Layer > New > New Layer ( Shift + Ctrl + N )
or you can click on the new layer icon in the layer palette.

The new layer icon in the layers palette
Now we will fill this new layer with 50% grey by going to Edit > Fill... ( Shift + F5 ) also make sure you set the
blending mode to soft light.

The fill layer dialogue box
Pick a soft brush ( B ), put it in airbrush mode by pressing on the airbrush logo in the top bar
and set its flow rate to about 10%.
This will make it so that you can build up the amount of dodging / burning.
All that's left now is to start brushing where you want the effect,
use white if you want to dodge use black if you want to burn.

The brush selection
There you have it, a non-destructive and easy way to doge and burn.

Rollover to see before / after