A good intro builds excitement and establishes expectations before jumping into a tune…
… while a turnaround (typically the last two bars of a chorus) keeps the musical momentum going and leads the listener back to “the top” of the next chorus.
A staple of boogie/blues is “that b3-b5 thing”… Don’t try to name the chords, but do understand the basic pattern as three lines of motion: 5-b5-4-3, 3-b3-2-1 and b7-6-b6-5…
