How to translate (jazz) improvisation on the french horn
I find it easy to improvise on an existing chord progression or melody with my voice, but I'm having difficulty translating it to the horn. It usually takes me a few tries to play the notes I'm visualising, by either finding the intervals or randomly choosing fingerings until I get it right, but that's too slow for live jazz improvisation, which is something I'm aiming to get better at.
I am okay at finding the first note (although I should still practice this), but I'm not sure which mindset to use to approach the rest without playing it a few times beforehand to get a feel for the notes. What can I practice to get better at this? I appreciate any advice.