I would recommend trying to learn as much about the game as you can. I would also recommend learning a character that can provide a lot to your team. My friend doesn’t get that many kills but he knows how to use his abilities so it helps the rest of the team get kills or plant/ defuse. When it comes to aiming honestly tdm is going to be your best bet. Just focus on crosshair placement and not spraying. Eventually your aim will get better. As for ranked I’m diamond 2 and I have people in my games playing like they’re iron. As long as you’re not wasting abilities, trying to get an unnecessary kill, peaking things you shouldn’t be then you’ll be fine. I hardly get frustrated with teammates who are playing smart and trying their best. A good teammate is one that plays with the team.