[scotty_b]

This is written following a question raised in another post on how to approach blues playing. It is by no means definitive, as there are many ways that we may approach the blues, from a one-chord vamp ala John Lee Hooker, to jazz-blues progressions crammed with every conceivable chord substitution and alteration.
In the attachments you will find a lead sheet for a basic blues progression, another lead sheet for a jazz-blues progression, and another attachment with various chord shapes that can be used to create some different textures when playing a blues.
Chord substitution is where we simply replace one chord with another. There are a few options with this, but for now we shall keep it simple. A 7th chord may be substituted with a 9th or 13th chord without any problem. I would recommend that if these shapes are new to you, you practice the various chord shapes and then try playing through the blues progression with the new chord voicings you have learnt.
The 6th chord to 9th chord sliding shapes is a classic Chicago-style blues move. If you have ever heard some Chicago blues you will recognise it straight away. SRV utilised such ideas too, such as on the tune ‘Empty Arms’.
As far as comping goes, a Freddy Green-style approach can work well (playing a ¼ note groove, strumming down on every beat), or letting the chord ring for a bar can sound great.
One last move that sounds great is the 9th chord move up from A to D, using a chromatic move up the neck to create tension and movement. It is one of my favourite blues moves.
Hope this helps those wanting to expand their blues rhythm playing.