as a 1 trick pony i hover from plat to low diamond. take this for what it is..
Bronze.. thing about bronze is to let your team mates die. if you are the smurf you have to let the bronze-ies just do whatever.. dont rely on them.. dont expect anything out of them. play the map and play your game. Most important - dont engage in any chat with them. they are mad because they arnt you.
Silver... people still have zero map awareness. abuse them. roaming is key.. people over extend all the time and it is really simple to catch them out. dont force engages .. as in ... if you go to gank or roam and the lane you are going to tries to engage before you are in position.. just turn around. fixing a bad situation sometimes just makes it worse.. you are the smurf .. dont get caught up in stupid.
Gold.. its a confidence thing. get your team fed and they will think it was all them. play the map. at this point people know how to start closing out games. team work is a maybe.. ping objectives and get the team where you need them. learn to count to 5. if you see a bad fight.. dont fight.
Plat.. people understand the game. people still over extend and you can still abuse people for not being where they should be. baits are key in this. use vision to your advantage. people react fast and try to take advantage of situations. you must become unpredictable. the number of times i have killed people because i sat in a bush till the enemy past me is beyond counting. People are still sloppy and dont check or respect vision.
Diamond.. absolutely hate this elo. this is where you will start running into boosters and scripters heavily. and if its not them its people who where boosted and on their way down. i have not figured out how to get past this elo and i have topped out at D4.
you have to start knowing not only the limitations of your champion but have to understand the limitations of the enemy champions. if you are good at multitasking. understand what objectives are going to be of value. know how to take advantage of when summoner spells are down. know cooldowns. know when the buffs are going to be up. small amount of info is key in this elo, as in location of junglers and any lane missing.
Watch the pros and how they move. Mid lane pros go through river and cut back just to see if you will push or just to make pressure on other lanes. just hiding causes pressure in other lanes. they are that aware. Dont back in view .. dont give any information away that you can avoid. only reason people in this elo do things openly are they shouldnt be there or they are trying to mess with you. sometimes i will start backing when there is one minion left in lane and it will die before i complete my back. so i cancel the back and hide in the bush. They think i am gone.. but i am just there so when they try things .. i am there. or i do it a few times till i want to do it..
Mess with other people backing. they want to back at certain item points. delaying them for even 1 second will throw them off a wave or ruin their rotation. be aware that it may be a bait. careful any blatant backings. jungler is right there.