Watch the Texas Blues: Rhythm online guitar lesson by Joe Deloro from Blues Rock Road Trip
This lesson is meant to illustrate the basis of various Dominant 7th Blues vamp shuffle tunes like, Pride & Joy (Stevie Ray Vaughan) and Bright Lights, Big City (Jimmy Reed). For example, think of P&J's riff (without the upbeat damped open treble strings) as a stripped down version of what you'll be learning here, and you're on the right track. In other words, although Pride & Joy alternates between a single note bass line and treble string chucks instead of parallel double stops as in this lesson, it's still primarily outlining the same chord progression.
In addition, the rhythm parts are primarily derived from the mixolydian modes of the I and IV chords, and enhanced with their minor thirds as passing notes. Overall, this offers a more melodic alternative than basic shuffle strumming or riffing. And once you throw in a "Don't mess with ..." attitude it starts to sound like it's probably from Texas.
As far as the solos are concerned, they're traditional and based on the pentatonic minor, but keep things fresh by incorporating position changes and open strings as well as a healthy dose of bends, releases, pull-offs and slides. The tunes and artists listed above would be the obvious place to look for further insights. Other sources from the past and present would include Freddie King and Robben Ford.