I just tabbed out the mixolydian scales. Mixolydian is a mode – you can think of it as a major scale with a flatted 7th (b7), or as a major scale started from the 5th note (If you use the C scale, you would start and end on G – G mixolydian.). It’s kind of confusing. The flatted 7th gives this scale a bluesy sound. It works great around 7th chords. Try using C mixolydian over the C7 going to F (in the key of C).
C (C major scale) > C7 (C mixolydian scale) > F (C major scale)
Nice. It sounds a lot better than using the normal B note over C7.