Watch the Dim Sum online guitar lesson by Jeff McErlain from 50 Eclectic Blues Licks You MUST Know
Here is a classic way to use a diminished scale in a blues. I begin the scale in bar 4 of the blues to create an altered I7 chord, I then resolve it to the IV chord on bar 5. This is something I, and many other guitar players learned from Robben Ford.
The lick creates an A7 with a b9, #9, and 13. This really adds some cool tension before the change to the IV chord. Not only can we do this with the diminished scale, we can do it by adding a A7b9/13 chord at the same time.