I look at it like this....
You can go round and round and come up with nothing by trying to "learn how to tune", or, you can solve an actual problem and very quickly learn how to tune without even trying.
As an example.... if you're going to move into a new place, you can either spin your wheels and go in circles trying to figure out everything you need and things you don't need to move..... or...... you can simply move in. As you need things, get them. In that way, the necessities solve themselves out and you conquer the problem from a purely functional basis. You get exactly what you need and nothing else.
For tuning.... find a problem.... either, the truck idles too low, or the pedal is too soft, too touchy, not linear, so on and so forth..... and solve that problem....
It is ONLY in the act of directly solving issues that you will learn how to tune. That is the only thing that will prove out the correct from the incorrect conceptions and simultaneously burn the solutions into your memory.
Find something simple, like pedal sensitivity, idle stability or something that you do not like and FIX it...
THEN you will learn how to tune.
That produces real questions with real answers that you will see and feel as you implement them.
It's like learning something like math. You can watch the professor do the problems ALL DAY LONG, but until you go back and work through them ALONE do you figure out first of all, that even though you watched 1000 of them get solved, followed right along and everything seemed fine, by yourself you can't solve a single one and most importantly, that ALONE, you can struggle and fight until you beat your way to the correct procedure.
Those offering information can only provide answers, you have to provide the questions, and those only exist through jam-ups and inabilities.
Find a problem, fix it...we'll help...
If you don't already have a bazzillion problems at the ready.... then why are you wanting to tune???
lol.
The sole purpose of tuning is solving problems that exist with the current tune.