With any tool other than the Type tool, press and hold the Spacebar to temporarily activate the Hand tool. Use the Hand tool to scroll...
To quickly access a color picker wherever your mouse is on an image, use the Heads Up Color Picker. Press and hold Ctrl-Option-Command and drag...
To change the opacity of a layer or a tool, tap the first number of the percentage you want, for example 1 for 10%, 3...
These shortcuts are what I would call everyday shortcuts: ones that help you navigate around and work with tools – regardless of the project you’re...