@Jeanette Now you are improvising over the changes. Clear harmony, tone and intonation as others have said. If you want to move into more rhythmic improv, then play a couple of choruses starting each phrase on a different part of the bar each chorus. For example, the "and" of 1, and, 2, and 3 and 4 and - in four four time. This will give you a feel of jazz.
Once you have this, then mix up where you start (and end) your phrases.
You could then add one chromatic note per change, for example, starting on the semitone below the first note that you play in the chord. If you are starting on the C of the A minor triad, then you could play B,C, E, A. This gives you four notes per triad chord change in the ii Vs, making it easier to play a line straight through.
Keep blowing, Bill