Mudflap Placement

[IdahoMan]

Is there any general strategy/guide/rule to follow regarding the placement of mudflaps on our trucks (proper protection/style)?

How low should they extend..
How far should they stick out on the side (if at all)..
How precisely "to shape" of the wheel-well do you like to cut them?
Where do you attach them? (I'm constrained to the original screw-holes though in my case)

Feel free to post pics.

I'm replacing the front mudflaps right now (Flaps are from NAPA, the screws from ACE). The back of my truck has 21.5"x15.5" flaps attached to rear bumper. I may replace those with back wheel flaps. Any material/brand recommendations?  As fun as I think it would be to go hog-wild and manufacture my own out of say.. spent shell casings (lol), I'm going to stick to a nice, clean generic look.