A friend asked me for improv advice. Here’s what I ended up telling him… Certainly not a complete list, but gives an idea of some of what goes into my own approach, at least.
1) Notice your breath. Breathe in. Breathe out. Continue this. Eventually, allow your fingers to begin to play. Pay as little attention as you can to what they are doing. Continue to watch your breath. If you get distracted (from this or ANY OTHER exercise or life process) gently forgive yourself for your wandering attention & return to observing your breath while your fingers wiggle around making sounds.
2) Pick an object, any object. I have used everything from a quartz crystal to a large wooden penguin. Try to interpret it spontaneously in music, with as little thought as possible. If you find that you are thinking too much, follow your breath while interpreting the penguin (or what-have-you).
3) Pick a scale. Move up it as you breathe in, down as you breathe out. Do this for a while, then try down as you breath in, up as you breathe out. Do it again using different scales (major & minor? pentatonic & whole-tone?), one on the way up as you breathe in, one on the way down as you breathe out.
4) Play as randomly as possible. Remember that total chaos is also a kind of order, so if there is NO appreciable relation between your sounds, that’s not really random :) It may help to do this slowly at first.
5) If you hear a plane or chopper over head, try to find what key it’s in & play along as though it were a droning bassline.
6) Open up any book & play the words you see written there.