Forget tennis balls, specialty shoe stores, night stretches, and drugstore inserts.
Go to the podiatrist.
I messed around with a lot of different things for several years -- then I finally had the podiatrist make me two pairs of custom inserts (which cost me only the co-pay for the doctor's visit). I've been wearing the first pair for four years now, and they're just starting to show wear.
The inserts don't fit in all my shoes (for example, goodbye strappy sandals), but they're wonderful. I wear Keds tennis shoes, boat shoes, and loafers. When I want to wear sandals, I can wear Chacos or some Sketchers ... they must have strong arch support, a high strap that comes near the ankle, and a cupped foot bed ... and they aren't quite as good as tennis shoes with the custom inserts.
This is important to understand too: If you're actively having trouble with your PF, your muscles are probably inflamed. The right shoes will MAINTAIN your muscles, but they will not "fix" inflamed muscles. The podiatrist will give you a (very painful but effective) cortisone shot in the foot. Take it: the shot will make a world of difference.