Slide guitar is physically easy in one sense — just drag a slide over the strings, and you can instantly hear the effect, right? However, proper slide guitar technique is not quite that simple. It can be difficult to control the sliding and keep the buzzing and rattling artifacts to a minimum.
Slide an object like a glass or metal tube over a left-hand finger.
Slides are usually worn on the third or fourth finger.
Rest the slide on the strings (not pressed down), directly over the fret wire.
Resting the slide on the strings and playing over the fret (instead of behind it as you do when fretting) takes a little finesse, but eventually, your intonation and tone will improve.
Change pitch by gliding the slide along the string.
This process produces a smooth, continuous change in pitch (sometimes called portamento).