Tricks include keeping your hands/feet dry, using antipersperent (avoid ones with aluminum which almost all include the 'natural' ones have), or soaking your feet in epsom salts (baking soda is another good soaking mix).  A foot powder consisting of fluffy tannic acid, talc, and bentonite can do the trick as well.

More tricks include parsley, chlorophyll tablets, clean footware (choose footware that breathes like leather),  and wear sandals.  One of the more outlandish cures is to use urine (a popular trick in WWII).

For sweaty hands try soaking them in tea.