You have to try them all until you find the combination that your happy with. My tone will totally differ with anyone else on Chordie. Try a combination, write it down, like master volume 10, volume 3, treble 8, bass 6, midrange 8 you get the idea. When you hear a combination you like put a star or something that denotes that you liked that sound. After you have a couple that you like play the same song through each setting and see which sounds better on that song.
Hope it helps.
Bootlegger.
If I could ad something then it would be to try all of your amp settings but don't change your guitar settings yet. For example, some guitars will sound different when you roll the volume knob up. I would try the amp settings with my tone off and volume about halfway and then go from there. Oh, and as Bootlegger suggested...write down the settings that work best for you...hope that helps...