Start making choices early and follow each decision to its fullest, funnest potential. Don't stick to structures. Intuition is the key to satori. They say that people who talk incessantly of sex are impotent. This is so with improv.
Talk is cheap.
True characters are rarely, if ever, one dimensional. Those are caricatures. Be careful with genre work. Sloppy genres are painful to watch, e.g., sci-fi, horror. Truth lies within the core of your being.