HiTork,
For street applications we make sure that the hold down clamp, the distribs base collar, and the block ( or manifold - on a GASP! V type engine ) are shiney metal and free of all paint and corrosion, and the engine has a good ground directly back to the battery.
On an all out race only application we drill and tap the distrib housing for a short 8-32 screw and run a dedicated ground wire back to the battery or to a known good ground cable that connects directly to the battery, whichever is the shorter distance. Admittedly this is a bit of overkill on the average street engine.
Another thing we insist on is all the electrical terminals on all wires are soldered and not crimped. You only need to lose one race or get stranded on a deserted road one time due to a failed connection to make a believer out of you.
Everyone has their methods and this is ours.
