Watch the Shake A Little online guitar lesson by Jeff McErlain from Essentials: Advanced Blues Rhythm
There's a lot going on here and it moves by pretty quickly. As with all the studies in this course, and in pretty much anything you'd like to learn, take some time and just listen to it first. Take it in and know what it's supposed to sound like before you tackle it. That may seem obvious, but I often have to relearn that little thought!
A lot of the motion and rhythm of the song comes from the right hand. We'll see that on just about every tune in this course. My right hand is consistently playing the eighth note rhythm whether I'm playing the strings or not. By keeping my right hand moving, I hopefully never lose the overall feel of the song. This can be little tricky, and my advice is to keep a nice loose wrist. That will help quite a bit. If the wrist is stiff or if the motion is primarily coming from the forearm, it won't groove!