Watch the Big Slide online guitar lesson by Jeff McErlain from Essentials: Solo Electric Blues
An important technique to master on this tune besides the slide basics is playing a note on the high string with the slide while letting the low strings ring out. The concept is easy, just angle the slide so it is only touching the high string! It'll take some practice to get it right and some bangs and rattles are a part of playing slide. Another important tip is finding the right slide for the guitar you are playing. If you have low action and light strings, slide will be difficult. You will also need a lightweight slide for that. A good general rule of slide is: "The lighter the strings, the lighter the slide. The heavier the strings, the heavier the slide." All within reason of course!