Adjustment layers in Photoshop
I have been working in Photoshop for many years. However, it was only this week when I found out one tremendous tool to work with paintings, illustration and any images. It's adjustment layers.
To use the adjustment layers, we need to press the half black half white circle icon at the bottom of the layer's window. Choose which adjustment you want to add and make changes. Once the layer was created, it influences everything below it. Here are some advantages that I found in the approach:
We can change the values of the layer when we want or just change the opacity of the adjustment layer.
These layers include a mask, and it is the most useful thing: everything we paint white will have 100% opacity and everything we paint black - 0% opacity.
I found this method extremely powerful for image-making: to create a nice contrast between the light and the shadow, to simplify values when I need to, to preserve image from being grey.