Blues is a simply style of music to play since it only contains three chords. Well is it simple? In an interview with Frank Gambale from his early days he confessed that he did find it hard to play blues. It is not that he could not play it, but he did find the phrasing hard. It is something which other players may be able to relate to as well: Improvising over longer chordsequences may be easier since the chords tell their own story. In music where you only have three chords you will need to get the right notes with the right timing to make the phrases come alive. You do not need to play fast but still you need to give those notes a certain feel to make is sound like blues.
For this short article a blues sequence which is based on a 12 bar blues but it is only played in four bars. Four bars is long enough for complete beginners to play. With a 12 bar sequence many students get lost and so is the joy of making music together. Give them four bars and they can still see where they are.
Play the following chords with a shuffle feel: E7 A7 B7 E7
Once you can play the sequence smoothly have a look at playing single notes which fit over the sequence:
Create a short melodic idea which fits over both the E7 and A7 and for the B7 you can create a short walk down and let it finish on the E7. Try using as many open strings as you can since this is possible and will make things easier for your fingers.
Once you get it right you get a feel for what you how you can play over a blues. Check out some of your favourite blues players to see how they do it. Do not get intimidated by the fact some players will play a lot of notes. It is better to play good melodic ideas which are slow compared to fast solos which just sound all like finger excercises.
Good luck and have fun.