11.50Your first ii–V–I improvisation routine

Loop:

Dm7 | G7 | Cmaj7 | Cmaj7

Then do four passes.

Pass 1

Chord roots only in melody:

D → G → C

Pass 2

Only 3rds:

F → B → E

Pass 3

Only 7ths:

C → F → B

Pass 4

Free C-major notes, but land on a 3rd or 7th whenever the chord changes.

This is excellent training.