Occasionally when creating a complex illustration, it is helpful to have options when hiding portions of a layer. To consistently use nondestructive editing, a single layer mask can be a little restrictive. For example, what if you have used a layer mask to create the outline of a shrub in the landscape, and a portion of it lies behind a column?

The answer is to use a second layer mask even though Photoshop only allows one per layer. Place the shrub layer inside of a group. A layer mask can then be applied to the group, allowing the option of a second mask. A section of the shrub can be removed without destroying the mask defining the shrub itself. Groups can be nested within groups, creating the option of several masks per layer.