Change the brush size on the fly
Want to change the size of your brush with out having to go up to the Option Palette? Just use the right and left bracket keys to quickly change the size of your brush.
The bracket keys also work on the pencil, eraser tools, clone stamp and a few others.
Want to change the softness of your brush? Hold down the shift and left bracket to soften the edges.
Bonus tip: Always use a soft edged brush when working in Photoshop to get better results.