Howdy M.G.D.All of the advice given above is real good, especially the listening to people stuff. Delta bluEs isn't found in tab or any other sheet music it's found in you. Listen to the old bluesmen and try to make your guitar sound like theirs and soon that guitar will tell you what to play and if you've got something to say, it'll tell you what to say.
The problem for most of us is that we start out wanting to sound just like Robert Johnson or some one but the magic of their music is that they all sound different. Every individual playing and singing the blues sounds different and the best you or anybody will be able to do is learn a few licks from them. Listen and learn all you can, develop your own style, play what sounds right to you and don't get hung up on technique or sheet music. The bluEs isn't on them pages.
One frustrated bluEs guy's opinion.
Gene