I've been going through a book put out by Hal Leonard Publishing: "Robert Johnson: At The Crossroads", transcribed by Scott Ainslie and Dave Whitehill. It's pretty accurate as far as I can tell from the songs I've learned. For slide playing, try to find someone who plays this style and who's willing to help you along. In the end, I've found that it takes a lot of listening to the early musicians just to get a feel for the stuff. I'd rather listen to someone who really feels the songs as opposed to someone who can play them technically correct. I'm not sure about other Mudcaters, but I found reading books about the lives and times of the early delta blues artists helped me to understand their music; and that understanding goes a long way in developing the feeling. I'd like to hear comments from some of the others; learning to play blues is a never ending journey.