I think sometimes we make this tuning stuff harder than it should be. It usually takes me 15 minutes to a half-hour to find the right arrow for a bow.
First I determine how deep the shelf of the bow is relative to center, then the type of string it has, the type of bow it is, longbow, hybrid, recurve, poundage at my draws length, and the weight and length arrow I want to shoot. I've been at this for 50 years so it's fairly easy to then determine the arrow I need based on those factors. Using Stu's calculator will get you to the same place quickly. The calculator just codifies and refines what a lot of folks have been doing by feel for a long time.
One difference between the way I approach tuning and the way many others do is that I start with a given arrow length, which is one inch beyond the riser at my draw length. I cut my arrows to that length and then tune the arrow to the bow with different weight inserts, adaptors and points, building out the side plate and/or playing with the brace height a little. Of course, the desired end arrow length and weight determines the spine and weight of the arrow shaft I select to begin with as well as what i think will be the needed weight up front.
I don' start with a long arrow and cut off small pieces until I get good arrow flight. There's a pretty good range of carbon spines now, and, of course, there's always been a wide spine range in wood and aluminum, so one should be able to pick a shaft deflection to start with that is pretty close to what's needed.
I seldom need to bare shaft, though I do if necessary. Theoretically, one might be able to fine tune even more, but my arrows come out of the bow clean, fly like lazers and hit where I'm aiming, both field points and broad heads. That's good enough for me.
Regardless of how one tunes, good form is absolutely essential. Without good, consistent form, tuning just doesn't work. We get too many wrong signals that we cause ourselves, and it can become very frustrating.
All I can say is keep at it. You'll figure it out.