Use a low sens (something like 800 dpi with 5 in game sens) and a large mouse pad. Use your arm for 180s and wrist for precise Tracking. Arm movements should be wave like and fluid and quick. Like a flick. And get used to your sens using custom games and bots. This is PC now so always ALWAYS work on aiming for the head. For heroes like widow and McCree, flicking to the target works well. Use wrist for small flicks and arms for large ones. Try and develop muscle memory after youre comfortable with a sens. What this means is that you always know how much the mouse has to move for the crosshair to get from point A to point B on screen without actually measuring the movement by looking at it. Meaning flicks and reflexive tracking should become second nature over measured tracking. If you really have trouble and have never used a mouse before, you can do some basic drills on aim hero from steam. It's like 5$.
But if you know the basics of using a mouse, stick to just practicing in game. Also make sure you practice actively over passively. Critically practice aim during games and only think about hitting your shots. Aim does naturally improve over time but you can marginally increase the speed if you just practice with purpose. Slayergramps is a top 500 ex console pleb who developed aim bot like GM level aim in only a few months after he made the switch. So again, it's definitely possible to do it super fast. You just have to keep at it and don't look at stats too much. Just see how consistently you can keep your crosshair on targets and that's enough.
