Watch the Melodic Minor online guitar lesson by John Stowell from Modern Jazz Improv
As I mentioned, I don't completely rule out using the diminished scale, but I want to avoid the pattern-oriented minor third or half step-whole step harmony that clearly sounds memorized and not creative or spontaneous. Take diminished ideas and break apart the patterns by dispersing the octaves. Mix some of those sounds with the appropriate melodic minor substitutions. A good tune to practice dominant 13b9 resolutions to minor chords (one of the cadences I demonstrate here) is Bronislau Kaper's "Invitation".