I endeavour to do some youtube videos on technique (and perhaps include some photos here), but in the meantime….
Legato is largely used to describe hammer-ons and pull-offs (using thy fretting hand).
Hammer-on: your finger-tip hammers down onto the string in order to sound a note (e.g. from fret 3 to fret 5). Typically if playing one string, you hammer onto a higher-pitched note from a lower-pitched note but some players like Alan Holdsworth (and perhaps also Brett Garsed) in fact can play using hammer-ons only (he’ll lift his finger off fret 5 and hammer onto fret 3).
Pull-off: your finger is already on the string and now “plucks” it in order to sound a note of lower pitch. E.g. pull off from fret 5 to fret 3.
Now, the trick is in mastering these techniques. Remember my top tip regarding tension and read on.
Perhaps I analyse this too much, perhaps not. I was held back for years because I thought that plucking the string (for a pull-off) meant that you had to have the note fretted with the VERY TIP of your finger such that your finger was arched a lot. Then when you plucked the string the finger pushed into the fretboard. The problem with all this is that the very tip of your finger is such a small area – you can easily miss the string (the target) – especially if there is any sort of tension in your hand! Arching your fingers too much also just doesn’t feel natural (though is used by classical players, and helps for allowing chords to ring clearly). At the same time you don’t want to fret the notes with the pads of your fingertips as I see some players doing (80s shred players with their fingers near flat on the fretboard) – imagine trying to play chords like that – half the strings would be muted! So there is a balance to be had.
Since I used to fret the string with the very tip of the finger, it meant that when I plucked the string, the fingertip would go toward the fretboard and underneath the string below it. In a way this produces a strong note and there is less chance of you sounding the neighbouring string if your muting isn’t up to scratch. But pulling off should not be toward the fretboard. Neither should you just lift your finger off the string as there is no force there. You should pull off such that your finger leaves the string at a 45 degree angle (toward the floor and away from your body) and finishes above the neighbouring string (or in that general area) so that it can come down for a hammer-on quickly.
Hammering on with the index finger trips some people up (myself included, at times!) and the biggest one of all is independence between the ring and little fingers. Try running up and down scales (musically) for 5 minutes, non-stop, on all strings (across strings and along one string – even string skip!) first with eyes open to monitor your hands and second with eyes closed to feel for tension.
One weird thing I encountered was my ring finger slanting to one side when I played. This was down to tension in my playing. Once I got rid of that, stopped using the very tip of my finger and start pulling off at a 45 degree angle, it “straightened itself out.”
To take things even further, I even consider the three parts of the finger (the main part attached to the hand all the way to the tip) and ask myself – what is producing the force? Surely the main joint? But if it is hammering down onto the tip area, does the tip “guide the finger” (pull it down) or what? When pulling off, is most force coming from a little flicking motion in the tip? Or is it due to the main joint again just pulling away? You know, even I don’t think I’ve convinced myself fully of the answers (I’m sure it’s a combination), but you can see I analyse it heavily. It’s a good idea to take a strong finger (the middle finger) and analyse what it’s doing as it usually performs its function well with little training. Learn from it!
Lastly, remember to close your eyes and FEEL what is going on. Remove any tension from your playing!