Watch the Take Your Time Solo online guitar lesson by Jeff McErlain from Essentials: Advanced Blues Soloing
Let's talk about picking for a moment. Pay attention to my right hand in the performance above to follow how I'm picking some of these notes. I'm picking fairly aggressively, as I want to get some snap on the strings. I like to set my overdrive on my amplifier or pedal to be sensitive to my right-hand pick attack. If I play more softly I will get less gain, if I dig in the gain increases. This is extremely important when playing the blues, as dynamics are essential to the music. A tone that is too overdriven loses dynamics, it may be perfect for certain styles of music, but not the blues.
This is the problem I sometimes have when I hear hard rock/metal guys playing the blues. Call me a snob, but it misses the essence of what the music is about. Listen carefully to all of your favorite blues players and make notes about how much gain they are using and the dynamics in their playing. Dynamics must be practiced just like a scale - literally practice playing as hard as you can to as soft as you can.