btw im writing this on the top of my head really quick dont judge me <.<
sorry i don't coach but if you want to get better these steps will help you become a better league player: (diamond 1 player 2 diamond acc and plat smurf)
establish what role you want to play:
jungle- most like a support for the lanes; junglers usually have most game presance
mid lane - mostly in this meta are high burst assasins (lots of plays etc.)
top- afk farming 1v1 pretty much whole game until teamfights plus splitpush / proxy
adc- main dmg output on a team ( should have strong positioning skills and should be able to last hit well)
supp- mostly having vision of map control (im not saying this is the only role that wards, but has map vision of major objectives/ choke points) dont understimate this role: this role can carry if played properly as well
what kind of player you are: usually the type of player you are influences what role you want to play and what kind of champions are best suited for you (assasins bruisers etc.)
some tips:
always have a constant understand of you games situation
ex. always look at your minimap
ex. press tab to look at the scoreboard and see whos fed, their main source of dmg output mag or att and pick appropriate items to counter their team
ex. when is ours and their buffs? baron? dragon?
knowing this can help you make plays: for example if your a jungler and you know the enemy jungler is ganking bot lane and you cant follow him up you can go counter his gank by stealing his red if you know it is up and then later follow up with a counter gank afterwards bot lane
ex. what lanes need help, if bot lane is in trouble and are getting pushed to tower, and your mid lane you can try to push out your lane and gank bot lane
ex. is your teammate caught? go help him out!
idk theres alot this was basically what was on the top of my head
gl hf m8!