Bill, it's easy - think about freedom (mobility) of pieces.
And always remember T. Wiswell famous quote:
"Moves which disturb your position less, disturb opponent postion most !"
When opponent center is weak, your side is strong !
I can't say it better then Tommy, and I can only confirm that I don't have any prefences and don't care of much - is it side or center move. Just trying to find the best move.
"Golden rules" somehow are limited in Anglo-American checkers and often there are more exceptions than rules !