A simple technique to use ( that sounds bluesy if used in the right context, ) is "Bend Tapping."

To play the "basic" bend tap, just use your ring and index finger of your fretting hand and your tapping finger in the strumming hand. Do a hammer on with your ring finger and then bend the note appropriately ( half step etc. ) While holding this bend; tap a note with your middle or index finger of the other hand. It has a very unique sound and can definately be used in blues music.

Hope that helps. Peace.