This article is from the Recreational Figure Skating FAQ, by Karen Bryden with numerous contributions by others.
Probably the most common cause of foot pain is boots that are laced
too tightly over the instep. The lacing should be snug but not so
tight as to cut off circulation or pinch the foot. If your boots feel
too tight (e.g., at the ball of the foot) even when the lacing is
loosened, the boots may be just too small for you. Have the fit
checked at a competent skate shop.
Many skaters (especially beginners) have a tendency to clench their
toes while skating, which can cause the foot to cramp. This problem
can also be caused or aggravated by boots that are too loose, keeping
your weight too far forward on the blade.
Another cause of foot pain is either excessive tightness or tendinitis
of the Achilles tendon. You can do "wall push-ups" to stretch this
tendon: stand about 3 feet from a wall and lean forward against it,
keeping your feet flat on the floor. You can also do a lunge stretch,
keeping your weight on your rear foot with the heel on the floor and
the toe pointing forward.
A common foot ailment that afflicts skaters is called "plantar
fasciitis", and it's a form of tendinitis that affects the bottoms of
the feet. Typical treatment includes resting the feet,
anti-inflammatory drugs such as ibuprofen, and custom orthotics to
provide more support for the foot.