Which blues guitarists should I listen to and learn their songs for influence. I already got Jimmy Page, BB King and Jimi Hendrix.
I work a lot with the blues as most of my students are Blues players: You can learn all the scales and music theory that you like, but the best way is to go with how you are starting.

Listen to lots of Blues guitarists and try and copy their styles. I was a massive Page and Hendrix fan when i first started learning guitar so I learned as much of their soloing style by listening to it and playing it by ear (it was difficult for me to read the notation).

B.B. King is great because what he plays is so simple. It is how he phrases his licks and his vibrato technique that are what you need to look out for and you can only really learn that by listening and trying to copy his sound.

if you like the Page way of playing check out Albert King, T Bone Walker and from King check out the great Stevie Ray Vaughan. Copying these guys will keep you busy for a long time!

The key things with the blues are the phrasing, the tone, mixing major and minor scales and how well you express yourself. It can take a long time to reach this state of mind, but if you think in this way you'll get good at playing the blues!

Good Luck!
Quote by StuartBahn
If you want something a little more sophisticated, try Robben Ford. He plays wonderfully and manages to almost entirely avoid cliche - a rare feat in blues music.

I agree to this statement. I'm a novice guitarist, but listening to Ford is always fun and interesting. Love his playing.

Other than those mentioned: Try Eric Claption, Rory Gallagher, or Joe Bonamassa.
Work on your bends and vibrato. Try to incorporate both blues, minor and major scales into your playing.

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I like John Lee Hooker for his rhythm playing, I also like Muddy Waters early tracks where it's just him and a guitar (before he was signed and had a band behind him) as really good exampls of rhythm playing. In terms of lead blues guitar I think some of the other posts have mentioned some really good names you should definately look into. There's also a quite recent blues guitarist who plays some awesome lead called Gary Clark Jr, I think his albums are more soulful and almost r'n'b but look up a live version of his song Bright Lights, the version I'm thinking of is at Crossroads festival and is on youtube, the second solo he does in that is pretty mindblowing.
I've also written a lesson that might help you, it talks about parrellel scales, which can give you some good ideas in terms of combining minor and major tones (the article is written thinking mostly in terms of chords and rhythm playing but you can use it to think about lead playing as well). http://www.ultimate-guitar.com/columns/music_theory/parrallel_scales_and_the_british_invasion.html
I think that first of all you have to listen to great blues guys, like the three Kings, Freddie, Albert and BB, Buddy Guy, SRV, Robert Johnson, Elmore James, JOHN LEE HOOKER, and dont listen to electric blues or blues rock only, explore delta blues or the old traditional blues of 1930s-1950s.
But remember: blues - good man feelin down.
feel it. i play my best blues solos when im reallly feeling down. think when you play with the heart, its creative expressive and energetic all at once.
Jimi once said i think, "blues is easy to play but hard to feel"