Watch the Ain't Sad for Long online guitar lesson by Corey Congilio from Slow Blues Guru
The most important aspect of this solo is the double stops. Not only are they double stops, they're what we would call major and minor third intervals. These double stops (or intervals) outline the chords that are going by and really work like a hand in a glove.
I'm using the number 4 position on my Strat, which utilizes the neck and middle position. This is a classic sound reminiscent of players like Robert Cray. Coincidentally, I borrowed the chord progression from Mr. Cray for this example!