should or should not-- ahhh it's improv...do what sounds nice.
Why don't you try playing Eb..F..F#..G Bb (B--add this if you on the G chord) C--try that over Cmin and then over G--the trick is to play them together as a run.
over the F7-- try descending from C-B-Bb-(A)-Ab-G-F-Eb...that makes a nice sprawling 3 octave run if ya play it quickly. Use a shell voicing of Eb A D--in your left hand (or C instead of D--if the 13th is too harsh sounding.)
over the G--this is just a triad? no extensions? than feel free to add some. Since you just played F7--we can assume or adjust that to be a G7--or 9--or 11 if you feel like it. try arpeggiating the chord with some additions-- like G..Bb..B..C..D..F..A (then descend)--Ab--G--and so on.
self-taught improv is rare on this site--as are self-taught pianists. most of these folks are trying for concert pianist status...and some here will succeed.
best of luck! send me a mp3 of what it sounds like
