Photoshop key commands make masking faster and easier. Here’s a list of the most useful ones. The best way to memorize them is to use them. (Note for PC substitute Alt for Option.)
The following key commands do not require clicking on the mask.
X reverses Foreground and Background colors
Numbers number keys change the Opacity of a brush
[ and ] makes a brush smaller and larger
Shift [ and Shift ] makes a brush softer and harder
Opt Delete fills a mask with the Foreground color
Command I inverts a mask
The following key commands require clicking on the mask.
Control Click displays mask options
Opt Click displays a mask in black and white
Shift Opt Click displays a mask as a red overlay
Command Click loads the mask as a selection
Shift Command Click adds the mask to a selection
Option Command Click subtracts the mask from a selection
Shift Option Command loads the intersection of two masks
Shift Command I inverses a selection
Drag & drop to move a mask from one layer to another
Option drag & drop to copy a mask from one layer to another
Find more Photoshop masking resources here.
Learn more in my digital photography and digital printing workshops.