From what I've noticed from switching roles to adc on a smurf the number one difference between myself and the enemy adc is that I know when/how to stop the bleeding. There's a favorite saying of mine which is that not having a lot of farm makes you weak while you having a lot of death makes the enemy strong. Might seem similar but it's really about knowing when you're supposed to be a carry and when you're supposed to be carried.

A fed toplaner can carry you when you have 0 farm and is level 1 if you just never die. A fed toplaner can't carry you if you're lvl 18 with 200 farm, if you also has given the enemy 3000 gold in deaths. Stop the bleeding is a must, especially if you're a solo queue adc cause you'll run into a lot of duo botlaners and your support doesn't give a fuck about you in low elo.

The most agency any low elo adc has is controlling the number of deaths they have. You'll get flamed for doing 0 damage and it's going to be frustrating, but that's the best tip I can give you. Other than that there's really no fundamentals needed in gold, as most games you'll end up as a walking gold pouch for the enemy jungler and midlaner