A turnaround is a two bar phrase which can be found at the end of each verse in the vast majority of Blues songs. Turnarounds usually begin on chord I in bar eleven of a 12 bar progression and move to chord V in bar twelve. A turnaround has the effect of finishing a verse while setting the progression up for the start of the next verse. Here are some examples in the key of A. Learn each one and then try playing a 12 bar Blues shuffle pattern and using the turnaround for the final two bars.
This is a variation on the previous turnaround. Instead of playing two notes together, the same notes are played consecutively, alternating between the third and fourth strings. With each new thing you learn, try re-arranging the ntoes or experimenting with the rhythms. If you make a habit of this, you will soon be inventing your own trunarounds and rhythm patterns. This is invaluable when it comes to jamming with other musicians.
The next two turnarounds are in the key of E. Once you can play these, try making up some of your own turnarounds. To get some more ideas, try listening to your favrite Blues ablums and copying what the guitarist does on turnarounds. Once you can do this, the next step is to create your own variations. The more you do this, the easier it gets.