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Overshoot and ringing are a side effect of a crazy fast switching response which is usually the result of wanting to waste as little power as possible in the MOSFET. To get that kind of noise you need some kind of reactance (capacitance or inductance) either from components, cables, or even the MOSFET itself.
A correct snubber can help. An incorrect snubber will simply make it worse.
How fast are you switching? Are we talking Hz or kHz? The other way around the issue is to slow everything down if the application permits. If you half the switching frequency then you half the powerloss in the MOSFET due to switching. With the new capacity you can slow the speed at which the MOSFET turns on which using a very gentle RC circuit at the gate of the MOSFET. This may eliminate the ringing even without a snubber.
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