'The blues' covers quite a wide range of differing styles and feels. There's a whole lot more than just electic guitar based blues.
Any of the artists mentioned above are worth a listen and the bass-playing worth a study (especially Ian Siegal's band, a personal favourite of mine). Whatever you may think of say, SRV, his bass player (Tommy Lee Shannon) is a class act.
Anyway, here are two other things I heartily recommend.
The 'Blues Bass' book by Ed Freidland. Includes a cd. Covers all the main progressions, turn-arounds, riffs etc.
Listening to the Paul Jones show, Radio2 7pm-8pm on Mondays. Or on BBC Play-again.
Last tip. Less is more.