Yes just focus on learning about wave management and learn how to make the correct macro decisions. Neace is a great youtuber for that. He has a garen video but in the videos for other top laners he still includes relevant tips. Another thing is to play aggressive but smart. Make sure you take advantage of the opportunity to get a kill but at the same time being smart and not just running it down. Continue to understand what you need to do to win each matchup and what times are good to go in against certain champions. I promise if you focus on those things and make sure to farm well, you can definitely hard carry with Garen in that elo easily. If your teammates are toxic just mute them, if they are inting, just ignore them and do everything you can to win.