Watch the One Note One String online guitar lesson by Geoff Hartwell from Guitar Lab: Electric Slide
This is the basis of ALL slide sounds – the fundamental first step. From the “Diddley Bow” and the Dobro players of the Delta, to the sounds of Elmore James and Robert Nighthawk in Chicago, through the Classic Rock sounds of Duane Allman and the Allman Brothers Band, all the way to the modern sounds of Sonny Landreth, they all have a common bond starting with just one note. Take your time with this one – this is the foundation of good slide technique and intonation. Pay attention to your tone, and stay relaxed. If you can get a really good feel for the basic principles in this lesson, then everything you build on that will sound great!