Simply put play more games, if this is your only acc you dont have many, some champs are still enigma for you. Study champ stats in lolwiki and try them all out to get a feel for them.
You play mostly ADC, so play more games as support, this will help you know what adc should and should not do in lanes, if your support goes harassing try to help him out and dont let enemy adc hit your support for free if he is in range, punish him, lane dominance is most important thing in lane
Play junglers to know when and how they gank to keep you confident and safe in lane.
Another important point is dragon, dont die off just before dragon spawns, and dont go farming when your team goes drake after successful gank, rush and help them, that tower wont go anywhere, but that drake will.
Also dont shy off from buying a ward or two, there is a limit how many wards support can place, and pink wards are limited, so get them when you feel team lacks vision or just get them for a heck of it.
Or i say it again, just simply play more games.
that horrible english tho, hope it helps pm me for more :)