I have not mentioned vibrato so far in this tutorial as I believe it is quite important that each player develops his/her own style of vibrato.
Hopefully having got this far into the tutorial you will have already tried to do just that.
I think the video gives a good illustration of how important vibrato is to slide playing - the tune sounds much more realistic ( like someone singing ) when the vibrato is applied.
Just move your arm up and down the neck fairly rapidly and you have vibrato - use your ears to try and keep in tune - once you have mastered a vibrato technique you can use it to fine tune notes as you play them ( by creeping up or down a bit as you vibrato ).
By " blurring " in terms of absolute pitch the note that you're playing vibrato tends to make it sound more in tune than the same note without vibrato.
Use vibrato on any held note or chord ; Try any of the following -
Wide Vibrato - go quite a long way either side of the actual note.
Narrow Vibrato - go a very short distance either side of the actual note.
Quick Vibrato - as the name implies.
Slow Vibrato - as the name implies.
Start slow then go quick.
Start with no vibrato then add it.
Sharp Vibrato - vibrato slightly higher than the actual note - this can add " edge " in certain styles.
A note on strings
Contrary to what's usual for guitar, old strings can aid slide playing by providing friction between the string and the slide so that the vibratoing can itself activate the string ( check out the "long lunar note" in Captain Beefheart's 'Big Eyed Beans from Venus'- especially if you're into alternative ways of using slide guitar )
The raw notes part of the video sounds particularly bad because the strings are pretty old - but the vibrato makes them sound fine.
Shaping notes is similar to what a good singer will do - sliding into notes rather than going directly to them. I have given a detailed description of the way I shape each note of the piece in the second tab/score.
Obviously where the note is an open string no shaping is possible.
I am in open E tuning for this one.