So, I am working on a tune called 'Fall' by Wayne Shorter. It has non-functional harmony and chord changes that aren't really in the standard ii-V-I form. Improvising over it isn't easy for a newbie like myself because you are processing a lot of stuff with a lot of overhead and trying target the right notes on the right beats and remembering the changes as well. What I've found is very cerebral things like this are best tackled early in the morning or at least the first thing you do when you start your daily practice when your mind is fresher. I then do the technique/exercise stuff last because it's not all that mentally taxing. It seems to kind of go against the norm of warmup/exercise stuff first but I found that I am as not mentally fresh when I get to the improv stuff. I do warmup, I don't just go at the improv part of my practice cold, I just limit it to something like a frew chromatic runs for a minute or two before I get at it. Hope this helps and isn't too much rambling.