Just watch your own replays. Take notes of what you do wrong and then after playing watch replays again and see how many of the things you did wrong you did again.
I have a silver friend I coached and I pointed out all of his mistakes for him and he just would not get it, would not improve. After doing this for a few weeks I told him to watch his own replays instead of having me do it for him and it finally started to click. When people point out your weaknesses you will think they are exaggerating it or you might think that it is just their opinion, but when you see the replay yourself and notice how big of a fuck up you made then it will be easier to tell that something neesds to be fixed.
Just watch replays and any time you die rewind it a full 2 minutes and then watch it on half speed or quarter speed and think about what you could have done differently.
Any time you lose an objective, do the same thing. Think about whether or not you actually could have done something rather than AFK farm a lane or walk in circles in the jungle.
You'd be surprised how many mistakes are actually pretty obvious. The only thing that I can see being taught is maybe how to set up runes / masteries and maybe builds / build paths.