Depends on what song you are playing really. A good clean tone is good place to start, and don't forget the compressor pedal to wring the sustain out of your guitar. Beyond that, you might want to have some overdrive on tap, and even some light distortion too. Your actual knob settings are based on the gear you are using, and will have to be found by trial, tweak, and a bucketload of patience. You have to tweak in very small amounts. It took me a long time to figure that out.

Set your guitar volume & tone controls at their midpoint. Set your amps tone knobs in the middle and go from there. On the amp, I suggest adding a small bit of midrange, and a little more than that on highs. If it sounds too thin, add a [u]small[/u] bit of bass to your liking.