Watch the A Blues online guitar lesson by Brad Carlton from Guitar Lab: Dorian Dominance
This lesson will cover the blues scale as an option when playing in the Dorian mode. The formula for the blues scale is: 1, b3, 4, #4(5), b7. Although the #4 is not a component of the Dorian mode, you can use this scale with great effect in your soloing. In the video I explain that this opens the door to chromaticism which is simply "connecting the dots". This melodic tool helps you create that ultra-smooth sound so prevalent in jazz. The concept of upper and lower neighbor tones is an important part of melodic embellishment and I encourage you to experiment with this by using both diatonic and chromatic tones.