I think that most of the better wheelbuilders will tell you that the actual process of building and aligning wheels is something they do using the brains in their fingers not the brain in their head.
Quoth FBinNY
Boy, is that ever true! I used to build wheels for a living. Never used any measuring tools then or now. This winter, after 35 years of doing little more to wheels than touching up the true or replacing a broken spoke, I built up a pair. It was a good thing I didn't have to rely on my brain which, like a sponge, is both absorbent and porous. My hands, though, knew exactly what to do.
Practicing on unimportant wheels is good advice, provided the rims are straight and the nipples aren't frozen. Try loosening all the spokes first, then tighten & true.
As far as using a truing stand vs a bike, a good stand makes it a little easier, but has no effect on the quality of the job. The only tool absolutely required is a spoke wrench. And if you are a very careful masochist, you can even forget that and use a good adjustable wrench instead. But you shouldn't.
Wheel building (& truing) is not an art. It is a skill which is learned through repetition. Kind of like riding a bike...