Switch between foreground and background colors
Click “x” key
Increase/decrease size of paintbrush
Click “[” and “]” keys to adjust size
Clcik “{” and “}” to adjust hardness
On Windows, Control + Alt + Right Mouse -drag left right to decrease/ increase brush size and up/down decrease/ increase brush hardness.
Make a copy of a layer
Hold down “alt” key and click and drag on object
Good tutorial on using the pen tool.
http://www.melissaevans.com/tutorials/how-to-use-photoshops-pen-tool