Instead of navigating through Photoshop's menus or moving your mouse to select a tool you can become more productive by using Keystroke shortcuts. 

While I photo paint, I leave my left hand on the keyboard and my right hand controlling a mouse or Wacom Tablet. 

Note: 

When Command is used on a Mac, that will be Control for Windows

When Option is used on a Mac, that would be Alt for Windows.

The rest of the keystroke shortcuts are pretty much the same.