Looking for help on how to improve general gameplay
So basically what's going on for me right now is that I'm stuck in a constant loop of losses, really bad ones. (1-3 wins out of every 20 games seems like the average)
I've been playing consistently for maybe 3-ish weeks now, although I'm not new to the MOBA genre as I've played DOTA/HOTS for maybe a year or two prior to getting into LoL. I started off playing with a buddy who is around the diamond area who gave me tips on what to build, champions to try, etc. After around a week and a half he let me go to play on my own to learn. I was doing pretty okay as a thresh/nautilus main support with him. I decided to start trying new champions (ADC, Mid, JG for the most part) and that basically ended up in me losing every game. I tried going back to support but this turned out to have the same issue where I lose every game (usually without my team breaking 10 kills).
I'm not sure if this is due to my ELO being higher than it should or just bad play every game. If anyone could provide some help or tips for my situation that would be great. I've tried pretty much everything to fix this. (watching pro league play, guides, custom ai matches, etc.)