Dave, first make sure the hum is coming from the guitar. Run a cord straight from the guitar to the amp, and then compare that with the hum you get when you add the pedal (wide open), and then add the other stuff you have in the chain.
Now, if it is coming from the guitar, then you have to check the wiring (is it shielded?) and make sure the grounds are in good shape. A LOT of guitars don't have shielded wire from the pickups to the controls, switches and jacks. Naturally, everything you can shield will help the problem. Copper tape (properly grounded) around the pickup coils
might help a little. But remember, the pickup is
made to "pick up" a magnetic field, and there's just no way of shielding the whole thing against stray magnetic fields.
When using an amp, my guitars hum a little, but not enough to bother me. In the studio, I seldom have a problem. And on the bandstand...it's lost in the music, for the most part.
Lastly, certain devices (such as lamp dimmers, neon lights, TV sets, computer monitors, flourescent lamps, and so forth) radiate a lot of electrical energy, and the only way to avoid a hum problem is to stay as far from these devices as you can...or turn them off!
