Hi Gary,
That's a broad question. Different effects give very different results, irrespective of settings. And even within a single effect, you can usually accomplish several different things.
I find it useful to first ask myself what I'm trying to accomplish. When I think of reverb, am I trying to extend an instrument's sustain? To place it in a space? Same space or different from the other instruments? Am I trying to make it less prominent in the mix? Do some experimental sound design?
Thinking through what I want to accomplish informs the settings.
Different effects answer different questions. For distortions, I ask myself if I'm trying to alter timbe. Or reduce dynamic range? Or bring it forward in the mix? Or tweak the tonal balance.
What musical task are you trying to accomplish?
Jonah
P.S. One thing I can recommend with certainty is to use shorter reverb times than the ones provided by the presets!
P.P.S. If you're really adventurous, try overdriving the effects internally by sending simultaneous duplicates of the same hot signal into the same send. You can even overdrive the analog output amp of the unit, which allows you to use the physical volume slider to vary the intensity.
Also fun to do Karplus Strong style resonator effects by reducing time-based effects' reverb/delay times to absolute minimum and play with high feedback levels. Then, all you have to do is send a 'tik' in.
You can get really creative with approaches like these.
