Agree with Guilherme's thoughts on page one. That said, I did survive giving hubby some instruction at his request when we were first married (he's also a pilot so I basically tried to relate it to flying). Most Invaluable was that I had a horse that truly anyone could ride and mostly, the horse taught him, or at worst, ceased to move when he couldn't figure out what the heck the pilot wanted.
Last year we went on a riding safari in S. Africa and so in preparation for that, hubby indeed decided maybe he'd best practice a bit since he hadn't been on a horse in over 10 years (and that, actually, was a Grand Canyon mule ride). So he borrowed my mare, put on his old Stubben, and thought gee he could just pick up where he left off in the early 80s. Well, actually, he couldn't, exactly. So he switched to western saddle and putzed around the arena. I gave tips when asked. Until the day he was flopping around at the trot, reins way too long, and gee, bounced his outside leg on mare's barrel, whereupon she dutifully picked up a canter. So hubby is puzzling through the fact that his reins are too long and turns mare toward a fence, thankfully only 2 feet, which she dutifully jumps. That prompted a 'help me' shriek, my response was, well, you need to help yourself, shorten your reins and ask her to stop. God bless the mare, she just kept cantering, wide eyed, 99 horses out of 100 would have taken steps to end the show. He successfully stops once he has his reins, but neglects to release, whereupon she does a decent reining horse reinback, prompting me to suggest he drop his reins, to which he responds, 'but you just told me to shorten them,' to which I reply 'yes, well, now I am telling you to drop them.' So he drops one, prompting a decent spin on the haunches to the right, so I add, 'now drop that rein too,' which he does, and poor mare comes to a standstill to the relief of both. He wasn't too amused when I accused him of scaring my horse, but he recovered soon enough and recommenced. And did have fun on the safari. And says I can't sell the mare, he may want to ride her again some time.
Now, when my younger son wanted to learn to jump at age 6, I did hire an instructor friend who came to the barn once a week. Ever so pleasant to have her yell at him while I did barn chores.