Watch the String Action online guitar lesson by Andy Aledort from Slide Guitar Power
The next choice involves what action - the height of the strings from the fretboard - you prefer when playing slide. Generally speaking, it's good to raise the action a little higher than normal lead-type action for playing slide (unless, of course, you prefer high action normally). Many players prefer a lower action than what is generally used when playing slide. One way to describe it is to set the action along the lines of standard acoustic guitar action, which usually is at least a millimeter higher than standard electric guitar action. This way, there is less likelihood of banging the slide into the frets while playing, as the higher action insures the slide will remain a safe distance above the fretwire. Higher action also allows players to dig in more (apply more force) with both the fret- and pick-hands. I prefer the unwound higher strings to be set slightly higher than the lower strings because I spend more time playing on the unwound strings than on the wound strings. But some players, such as Derek Trucks, prefer very low action so that when switching to conventional fretting, it is easier to play.