Plantar fasciitis can be a very frustrating problem. It essentially comes on when the stress placed on the fascia exceeds its ability to handle said stress. This can be the result of tightness, weakness, and/or an excessive increase in activity.
Initial treatment needs to focus on reducing the stress on the fascia (such as arch supports, more supportive shoes, taping, activity modification, etc), and pain control ( ice, pain relievers, massage, needling, acupressure, etc).
The next phase (often can be done concurrent with the initial treatment depending on the severity of the pain) then involves addressing the causative factors such as flexibility and strength issues. Flexibility primarily involves calf stretching and plantar fascia stretching, and possibly the use of a night splint such as the previously mention Strassburg sock. Strengthening primarily involves the muscles of the foot (intrinsics). Toe curls, picking up marbles, and short foot exercises are all good here. Also, as long as it doesn't cause pain, going barefoot or walking in sand are great strengthening exercises for the foot.
Keep in mind, the more you support your foot, with orthotics, very supportive shoes, etc, the less stress you place on all structures of the foot-including the plantar fascia. While this is necessary in the acute, painful stage, it is counter productive in the long haul. Increased support means your own support structures are doing less and therefore getting weaker-or at least not stronger. This is easily seen in cultures that don't wear shoes, where the incidence of plantar fasciitis is near 0%.
That said, if you are going to be doing a lot of hiking on rugged terrain, wearing a good supportive boot and possibly a good insole/orthotic may be a good preventative move, but not something to use on a daily, year round basis.
Best of luck to all, been there myself.
