Keep the gain down and the volume up. This will give you a less heavy metal tone. The classic blues thing is to find the point where the notes are just breaking up though this can be achieved by playing with the volume on your guitar, turning it up when you want the note to break up and back down when you want the sound to clean up.

Play with the Treble middle and bass until you find something you like. It is hard to give absolutes as the exact tone will depend on 1) the guitar and 2) the way you play it. Id be tempted to keep the treble down and start by boosting your mids though the effect of this will also depend on the type of amp. You may also find that turning up the mids will alter the distorted sound you get, more mids = more breakup, less mids = cleaner sound though this will depend on the way the amp is wired.

You might also want to use your coil splitters if you have them (tap switch) for a more Hendrix (neck pickup) / SRV tone.