I need help performing better in league games.

Recently I have quit playing, and ever since I've been playing I have been performing a lot worse. I've started at S4 and stopped at S6, and am now coming back about a month ago. I need help doing better in my league matches because I want to start playing ranked and expanding my roles & who I can play right. For now, my highest mastery champions are all auto attackers, and, I know, I suck. Any help is greatly appreciated.

Message me on discord as well, I'm very active on there: Quietra#6663