Need Help Wtih Gameplay

New season has started and I was bronze up until the last couple of days of the season I finally made it to silver 5. It basically boiled down to being in bronze 5 for so long that I got fed up and I actually wanted to start winning and doing good as a solo player as well. I didn't want to just win by being carried I wanted to know that win or lose I did my best. So I started looking up tons of youtube vids on how to play better. Eventually I went from a negative KDA and 32% win rate to a positive KDA with a 49% win rate. I'm not good by any means but I'd like help from the more experience players who are in higher elo to better explain on how to prioritize objectives at certain parts of the game. Sometimes I'm getting all the towers for my team and its a sure win but we still lose. So I wanted to get some help as to when my team has the advantage to keep it and ensure a win. Also if we're losing how to comeback and gain the advantage as well.

Didn't want to make this long but if anyone high elo player could help me out I'd be extremely grateful. Username: Fear Mr Lemon