Learn deeply enough that improvisation stops being guessing.

Guessing and improvising look identical and come from opposite places. One is filling a gap with nothing, the other is applying deep structure fast enough that it does not feel deliberate. The difference is entirely how much genuine understanding sits underneath the moment.

If you find yourself improvising badly, go back to the underlying principles rather than practising more improvisation. Depth is what turns a fast response from a gamble into a judgment.