Any advice for being an adc?

I know there are a lot of videos on how to be a better adc and stuff like that but, I would like to get some more advice from other people who either have some experience being an adc or just main that role in general. Recently I have picked up three adc that I am comfortable with: Jinx, Twitch, and Varus. Here's some questions I have: Should I pick up more than just the three champs I'm comfortable with? What would be a good build for the champs that I am comfortable with? How should I approach team fights with each champ I'm comfortable with? (Sorry most of these questions revolve around the champs I play but if you could answer them with anything for an aggressive player because I tend to get too aggressive.) If I'm an aggressive player can that be good or bad or should I try and balance it out? If I should pick up more adc champs are there any you would recommend to try? In lane should I trade with my opponent often or should I try and get more cs? Well so far that's all the questions I have. If any of you could answer them or give any other tips or advise that would be nice. (Also this is my first time posting here.)