Oh and youtube channels and videos and stuff- don't count for a darn thing at this point. Learn things in person and if you need help get help in person (and have them show you, not just fix it).
There are so many things, like putting on a saddle. Well you need to position it right, and do the girth up nice and snug, but not enough to make the horse hate you, not too hard, but while you're at it you need to (subconciously is fine, and I promise you WILL get to that point someday) evaluate the fit, look for anything awry (a worn bit that could snap, a burr on the saddle pad) watch your horses reaction to make sure nothing's bothering them about it, etc. All tiny little details that even the best rider doesn't often do conciously (at least not daily) but would definitely notice if something was "off". It's really just experience.
I think it's great that you're willing to board as you learn, you definitely have the right approach and that's all that's needed! Do keep in mind regarding instructions, ALL things in the horse world are NOT created equal!! There may be more than one way to do something, but there is also a definite right and wrong way. I worked at a lesson barn that was pretty scary. I also saw someone with lots of money and less sense buy 3 horses off the bat as a complete novice, needless to say that went south. But you sound like a practical person! Common sense and listening to your gut goes a long way.