Never can have too many keypads!

-As others have mentioned, stick with the theme.
-Mixing scenes and rooms can add to confusion. So don' be afraid to have 2 keypads in important areas. One would do loads/rooms and the other could do the scenes.
-Top button should always be on for that room. This doesn't always mean every light. When I go into my kitchen at night, I don't always need the upper cabinet lights, the toe kick lights, the pendants, the general recessed, the range hood light, the undercounter, etc, etc. But that is me...
-The button should always turn off the area or room you are leaving.
-Only use "All Off" at entrance points. I prefer not to put those on the bottom button because you don't want someone "easily" pushing that button when others are home. 2nd up from the bottom.
-Don't be afraid to use LESS buttons. On/Path/Off for example.