Btw, i am also bronze so listening to me may seem stupid, but i can't resist to anwer this.
Tip 1 : never blame yoir failure on others. If you made a stupid play, don't try to find blame on others but yourself.
Tip 2 : record your games if possible and gi back ant take a look at them. (That i don't do myself as i have no time for that)
Tip 3 : be polite when you request things from your teamates. Make sure you ask nicely as they have better odds of doing it.
Tip 4 : never, and i mean never engage in situations where your are outnumbered, even if you are confident enough that you can win, always wait for the whole team to start fights. Especially in late game, as your opponents build more items and the item discrepancy is smaller.
Tip 5 : learn your role, as an adc you never intiate yourself, never face check bushes. You will be chopped down if not killed and you will provide no help when the fight starts.
Tip 6 : have dragon control. This is why bot lane takes two players in case you ever wondered. Have a ward at dragon and make sure you have control of it.
Tip 7 : farm as best as you can. There is never enough. Watch the lcs and aim for no less than what they do. Game after game have marks. 10 minute mark, 20 minute mark,40 minute mark and so on. And make sure you do your best to be as close to that as possible.
Tip 8 : learn how to manipulate minion waves, learn when it's good to only last hit and keep the wave closer to your tower or if you need to hit it harder and push it towards enemy tower. If your jungler comes for a gank, freeze the wave so that it moves closer to your tower so your jungler has more room to work with.
Tip 9 : build accordingly. If you fight a tankier comp rush your last whisper (4 or 5 th item) if your fighting less tankier comp leave last whisper for last item. Always carry some lifesteal as it's your best shit at staying alive at extended fights. Also i wouldn't recoment infinity edge unless you are going to get another crit chance item to support it. An infinity edge by itself cant do much good for you.
Tip 10 : play all roles so that you can predict enemy locations, movements. More specifically play alot of jungle. This will make you understand it better and thus know when it's safe for you to over extend and when a gank is coming. Even without wards you will be able to predict incoming ganks.
Tip 11 : Never start fights with others in chat. Even if they are stupid dont type. More typing means less playing and you dont want that.
Tip 12 : DON'T BE AFRAID TO DODGE IN CHAMP SELECTION. This is the golden rule. Dodging does NOT affect your mmr which means it's ok to do it. If you see people trollpicking or flaming in chat before the game even starts, dodge. You lose little lp but you save your time and it's a 90% loss anyways.lose 5 lp instead of 15 + 35 minutes of your life seems a fair trade.
I am sure i can think of more tips, but it's not coming in my head right now. I hope this helps. I know im bronze too, hopefully by next season i won't be.