Watch the Billy Boy: Solo 1 online guitar lesson by David Blacker from Swing Blues Survival Guide: Lead

Notice how the licks over the I chord in the first four measures setup the transition to the IV chord, with the last note falling on the dominant 7th of the I chord. The dominant 7th of the I chord is a half step above the major 3rd of the IV chord, so it really helps signal the upcoming change and lets listeners know that you know exactly where you are within the progression.

Take a moment to analyze the riffs that happen over the IV chord. If you're a blues player the tendency is to think of them as 2nd position (Albert King) blues box licks. The idea with swing blues is to think of those notes as they relate to the 4 chord. Lastly, really internalize the 7th to 8th measure ascending double stop line and the II-V-I turnaround, as these are really important passages within a swing blues, and will open up other ideas for you down the road.