I think that if you want to do your live in total improvisation you Must really perfectly know you machines, your kit or synth sounds. It’s possible.
the easiest consist in preparation of patterns and sounds wich allow you large amount of tweaking possibilities with reasonnable and unboring vafiations in view to make public have a good time listening to you.
i remember an interview of Autechre in witch they declare that the stuff was ready before concert and they just ad variations to the sounds and routines (at the period when they play live with MD & MnM).