This particular blues guitar riff has been widely used. Steve Ray Vaughn has used this riff tons of times. Songs like “Pride and Joy” and many others have used variants of this riff. This guitar riff is based on the E chord.
The guitar riff starts with a slide from the 3rd fret going to the 4th fret of the 3rd string. Then, pick the 2nd string on the 3rd fret. You can also pick both strings (3rd and 2nd) which make up your minor 3rd. Move down to the 2nd fret and bar the 3rd and 2nd string. These notes make up your major 3rd. Then, openly pick the 3rd and 2nd string. Next, play the 4th which is a bar on the 4th and 3rd string of the 2nd fret. After that, pick the 3rd and 4th strings open. And then, finish it up with an open E chord.
To summarize it up, it’s a slide on the 3rd string from the 3rd fret to the 4th fret. Then a minor 3rd (3rd and 2nd string on 4th and 3rd fret, respectively); a major 3rd (3rd and 2nd string on the 2nd fret); an open pick (3rd and 2nd string); a 4th (4th and 3rd string on the 2nd fret); open pick (3rd and 4th string on the 2nd fret); then an open E chord.
These sums up the notes being played in this guitar riff. You can try making your own variation on picking the strings depending on your feel.
Groovy Blues Guitar Riff Based on 3rds in E:
Watch this groovy blues guitar riffs on youtube.