Below I’ve compiled a graphic (for both Windows and Mac) showing my most commonly used shortcuts. I come from a landscape photography background but these shortcuts should be useful to those working in other genres as well.
Learning these shortcuts will save a lot of time. Whilst it might seem tedious at first it will soon repay the investment. The masking shortcuts in particular will allow you to paint or modify layer masks relatively efficiently.
Here are the shortcuts I have proposed laid out in text form should you wish to simply print the text versions. This are the Windows shortcuts, but to change them to Mac just replace Ctrl with Cmd.
Ctrl + X : Cut
Ctrl + C : Copy
Ctrl + V : Paste
Ctrl + S : Save
Ctrl + Z : Undo
Ctrl + Alt + Z : Step Backwards in History (repeatedly undo)
Ctrl + + : Zoom in
Ctrl + – : Zoom out
Space : Hold and mouse click to move with hand tool.
0–9: Set the brush opacity between 10% and 100%
[ : Smaller Brush
] : Larger Brush
Shift + [ : Softer Brush
Shift + ] : Harder Brush
Ctrl + I : Invert
X : Switch Foreground and Background Colours
Ctrl + T: Free Transform
Ctrl + J: Duplicate Layer