Here is a practice track for all levels of guitar player. It is a piece in the Dorian Mode. Use the notes of the C major scale to improvise a melody, however the root note will be a D, and the notes of the D minor triad will be prominent! The practice track is four repeats of a 16 bar chord progression:
||: Dm |Dm |G |Dm |
| G |Dm |G |F |
| G |F |Am |Dm |
| F |G |Am |A7 : ||
Note that the 16th bar, just before the repeat, introduces the C sharp in the A7 chord, so for this bar use D melodic minor instead of the Dorian mode (i.e. just substitute C sharp for C in the Dorian mode).
Have fun!
Rob