I haven't played FPS in 5 years after I got shoulder/arm/hand pain. How do I get good at aiming again?

I suck at TF2

Aiming is a scam, let enemies walk into your crosshair

it is hard to say what skills you are lacking without gameplay footage
heres a couple blind tips
>when you have time, aim where you expect players to be, like at doorways that a player could concievably walk through at any moment
if your crosshair is closer to your target when they appear, you will have less trouble adjusting your aim to shoot them
>use your movement to do fine adjustments to your aim instead of your mouse
it is easier to make small adjustments to your crosshair on a distant enemy by moving your body vs moving your crosshair. see image