Use your trinket.

It should be slightly apparent since all roles come with two free wards. Do not rely too much on your support toward the jungle or possible ganking spots. A lot of ADC players depend too much on their support toward but they shouldn't. What if the support disconnect or what if the support does not have enough wards? It's never too much toward.

Over-pushing or overextending.

Over-pushing or overextending when you do not know where the enemy team bot lane is, or their jungler makes it very risky for you to die. If you're alone just push the way to the middle and leave some alive and go back to base to buy new items. If your support is around, make sure you have the try bushes near the river warded. It is also good if your jungler is around to help you get the turret.

Target their support.

Most ADC's and support are squishy. If you want an 'easy' kill, focus on their support (as long as they are not tanky) when you are ready to fight them. The same thing when they jump on you, focus on the support because they are the ones keeping their ADC alive. It may not be easy, with their ADC attacking you, it should help you survive (hopefully).

Stand behind your tanks.

ADC's are squishy. Quick to die but do a lot of damage. ADC's should stand behind their tanks because they have the range to attack the enemy from the safety of the back lines were the tanks can take the damage for you. It's a common mistake with new ADC's player to be in the front line attacking the enemy tanks when they should be in the back line attacking their support and ADC's first then jungler then their tanks.