My main ADCs are Jhin / Ashe / MF. Jinx is making a comeback for me too, I like lategame scaling ADCs a lot because high pressure situations are fun.
If you want to be good early / mid, why not give Lucian a try? He's a good duelist as well so he has a better chance if he's stuck off to a side against an assassin. Twitch isn't bad either, decent at all points on the game really.
Best tips I can give are to pick 3 ADCs and really learn them. Learn your matchups and build variations on them. If you specialize at first it makes it very easy to pick up others later on.
Always be checking the map, cannot stress that enough and you can apply that to any role. You're very fragile and if you're not paying attention any mid mage or assassin will just pop you if you miss their roam. Help your support keep that river warded, I see way too many ADC players ignore their trinkets regardless of skill level.
In teamfights hit what you can hit from a safe position. NEVER try to walk through the enemy frontline, it's not going to be worth it. Sometimes that means you're hitting a tank, but it's better to do that than die because you made a huge positioning error. You do zero damage while dead ( minus Kog / Karthus ). Stick near your support or any defensive champion and kite as much as possible.