First of all, sorry for my broad English, I’m French (nobody’s perfect).
I don’t completely agree with the point of view of Jaalmadakan and Ihatederekreed. Or maybe, I just agree with the idea that if the audience is fully intoxicated, you can do anything in any order and it will be OK. So, if you push this argumentation to its end, come to the club with a lot of pills, drop them in all the glasses, and wait for the people to be completely stoned to play any bullshit without any musical content 
But I think it would be very disappointing for you, first of all…
My opinion, based on years of lives acts in solo or with friends in free parties, is that improvisation is the most difficult thing to do if you are in front of a demanding and erudite audience, and most of the time, this is the case. I don’t want to put you under pressure for tonight, but most people will perceive the difference between a structured live act (even with a strong part of improvisation), and the guy who comes and discovers its machines during the live act and have no preparation at all. I think there is a minimum of preparation needed, in order to be able to “tell a story” with your music, and not only to play “techno”, “tribe”, or “dubstep”, or any of the classical musical genres you can imagine.
Hard work and strong preparation is, in my opinion, the only good condition to play good improvised music. When I play live, I always have sheets with notes that correspond to the progression of the musical ambience I want to develop, what breaks/drills/fills, etc., will fit with what pattern, what sample to use before and after what other sample (I often use samples of poetry, or political or surrealistic speeches, or theatre, etc.) in order to add sense to my music, and it’s like in jazz music: I’ve got a sort of written score (but without any musical note on it), and I do improvise a lot in the frame of this strong panel of constraint.
So, my advice is: like in BDSM, if you want pleasure, have pain first 