Once you know a
blues scale, the next step is to play some melodies over a 12 bar blues chord progression. This style works so well because it's built from the most fundamental chords; the I, IV, and V chord. Although for jazz and bebop, this progression is often embellished with more
complex chords. Here is the structure of the basic blues progression:
I / I / I / I /
IV / IV / I / I /
V / IV / I / V /
The I chord is built from the first note of the key your playing in, the IV chord is built from the fourth note of the scale and the V is, yes, built from the fifth note of the scale. Also it should be noted that the chords will often be dominant 7 chords which helps give the chords a traditional "bluesy" sound.
Here is the basic blues progression in the key of C:
C7 / C7 / C7 / C7 /
F7 / F7 / C7 / C7 /
G7 / F7 / C7 / G7 /
It's a simple progression that has a nice dynamic peak at the V chord. It's also fun to come up with phrasing ideas to try such as: play a simple short melody over the first 4 measures, play that same melody again over the second 4 measures, then play the "answer" to the first melody over the final 4 measures. Also notice that each note of the blues scale has a different "sound" or "feeling" over the different chords.
It takes time to really learn the chords to the point of not having to think about them, but once you do, you can really express some satisfying soulful music that sounds great!