To me formal teaching would be ideal, if I could go back in time (and have money), I would have did that from the start but my family didn't have much disposable income to pay $30 a twice a week for lessons. I had to learn through books for bass and guitar. When I got my first job and my license, I took bass lessons for slap and increasing my speed. That was my junior year of high school and I wouldn't discover youtube until my senior year in 2009. Even though it came out in 2005, I only spent my Internet time playing Runescape with friends. If there were lessons in the early years of YouTube, I missed out on some free resources. I still use some of my books for references. There's nothing wrong with using YouTube videos to learn an instrument but since there's no accountability you might do something incorrectly, at best you'll have to correct it by undoing the muscle memory and at worst giving yourself carpal tunnel and deal with the bad wrist pain. I've had that for a while now and not because my fretting was wrong, I had fractured my left wrist 2 different times like how a people crush a coke can when I was a little kid so I developed it at an early age, probably some arthritis too because I can tell before a weather system comes through based on how bad it hurts. I've seen some other people offer a few free lessons then turn around and ask for money on their own website. At that point just get the formal teacher, you might have to shell out a little more but at least the teacher will correct your mistakes.