| The contour control cuts mids, to accent lows and highs. Turning it fully counter-clockwise to zero disables it, and that's where I'd start. Work with the other controls, then add some "contour" later if needed.
The mid and mid-shift controls work together as a semi-parametric filter. A setting of Mids -2, Mid-Shift 1k mean you're cutting by 2db at 1khz. To get familiar with what this circuit does to your tone, try setting Mid to max boost (+15), then sweep the mid-shift control from one end to the other. Repeat this experiment with Mid at max cut (-15). These are extreme settings, but should help give you a feel for what the frequency ranges sound like, and hopefully, a better feel for where you want to boost or cut.
I more often use mid controls in boost mode, most commonly in the mid-upper bass range. But sometimes it's more helpful to cut, such as when you've got a room resonance to tame, or a region where the speaker sounds nasty. Since your shift only goes down to 200hz, it's more likely to help with the latter.
And if you're playing with a pick, I'd have the treble/high control lower, so you don't get so much pick noise. Obviously, a matter of personal preference. | 
