Keyboard and mixer volume levels

[Opaloka1974]

In a setup where an arranger keyboard is connected to a mixer via 2 jack plug leads and there is a rotary volume control dial on the keyboard for output volume, a rotary dial on the mixer for adjusting input signal volume and a rotary main mix dial for adjusting the output volume to active speakers. Is there a preferred setting for these 3 dials, for example should the mixer input signal be kept low and the the main mix output be low and the keyboard dial high. I would only want to adjust the volume on the keyboard when playing it.