For a beginner I would:
Make sure they have a correct left-hand arch, thumb around the centre of the back of the neck. If you bring your thumb up and over, it brings the reach of your fingers back and grips.
Teach them how to use the right amount of fretting pressure, which is less than you think, to avoid the grip.
Avoid the flying fingers by concentrating on keeping them close to the board, less recovery time for the next note.
For the right-hand:
Alternating, alternating while crossing strings. Raking comes naturally, alternating while crossing does not.
Anchoring the thumb as a mute.
Tendons and ligaments work better in straight lines, keep the wrist and the fingers straighter.
None of those are absolutes, it depends on what you are playing.
Older students I took on an individual basis, some liked rock/metal and were not interested in playing other stuff, or some liked chart/blues/funk etc.
I would teach then a tune they already liked, which pulled them in, and later show them the parts which were made up of the major or minor scales I had taught them. So that they could hear and visualise how they were applied in music, scales on their own don't mean much.