Whether you use a PC or a Mac with Photoshop CS, a keystroke or two can change the size of your brush, how opaque your tool is, and even paint a line. The following table shows painting commands for both systems.

Action PC Mac
Increase brush size ] ]
Decrease brush size [ [
Change opacity of tool in 10% increments 1, . . ., 9, 0 1, . . ., 9, 0
Paint or edit in straight lines Click, Shift+click Click, Shift+click
Erase to History Alt+drag Option+drag