Wanting to Get Better

Ok so realistically I have not being playing for that long,my time only amounting to about a year and 1 fourth. Still I have a desire,just like most league players at some point to want to be a better,smarter, and overall efficent player. Right now I'm currently a jungle main. Kayn being my little one trick that Ive had so far,but as of recently I'm wanting to start to become a Nunu and Willump Main,because it fits my rather passive kind of play style (Which I'm hoping to change). The only issue is that I cant seem to make good decisions in my games.Sometimes I can be the literal definition of a brainless ape, doing things without a second thought or if without a useful purpose as to helping the team. So I really dont know how to help myself in the best way. I keep watching guides on YouTube and looking on other LoL-related sites (Op.gg or U.GG), but whenever I go into my games I never seem to be able to apply what I know or should know to the actual process. So if anyone could give some advice or steer me in the right direction I would be sincerely grateful.