Help with Improving

I usually solo queue ranked, really embarrassing but I got over 1000 hours and only ever peaked silver. Recently started aim training and looking at my replays. How do I improve the fastest as a player (mainly mechanics) My aim is a little on the weaker side but I can tap heads on a good day, I think my util usage is solid, and my game sense is a little shaky. I got good map and agent knowledge as well. Also what’s the best agent for solo queue ranked? (Currently bronze 2)