To improvise, you first realize that you are already improvising. To improvise, you first realize that there is no such thing as something that's truly improvised, nor not improvised at all. To improvise, you first realize that improvising exists in the act of doing, not in the thing done, not in the value of the thing done. To improvise, you first realize that improvising is being. To improvise, you let yourself happen, and it comes out as what someone might call improvising. 

Free Improvisations (more found on my Youtube):

Improvisations based on suggestions by an audience: