Accept randomness
Also 'yes, and' randomness. Expand your circle of expectation to contain weirdness.
Improvisers often gravitate towards setting scenes in familiar, real-life environments. However, it's important to remain open to the possibility of departing from reality, while still considering the concept of the absurd circle (as discussed in the Absurd Circle).
Keith Johnstone once crafted a (scripted) play where the main character preserved his sperm for future use, accidentally lost one seed in the castle moat, and embarked on a wild pursuit as it grew into a whale-sized creature, engaging in a battle with his master.
Why don't we dare to improvise such extraordinary scenarios?