-You can't rely on your team at lower ranks
-Pick champions that can carry. I don't think that it is any coincidence that the champions with the highest win rates all have good aoe/cc. Just make sure you are decent with the champion also.
-learn to know where the enemy team is or isn't
-If 5 members of the enemy team are all mid at 15 minutes into the game, see if you can farm or push another lane to take turrets. They MUST stop their 5 man siege if they want to stop you from taking all of their towers in that lane. This puts the pressure back in your favor. Just don't forget to recall or don't overstay your welcome if you know they are coming to you. Keep in mind that this early in the game, it does not take 5 people to defend a turret. Especially if the champion you picked has good wave clear and pushing power.
-Upgrade your trinket ward to make it 100% easier to split push if the enemy team does decide to play ARAM in the mid lane. I would stress wards more but in nearly every game, wards become a wasted investment because your teammates don't use the vision to their advantage at lower ranks.
-If you see a fight happening or someone getting caught, don't run to it every time. Use that as an opportunity to steal the enemy's jungle, push a lane up, or even take a turret. If you run to fights that are happening pretty far away, you only waste time and continue to allow the enemy to gain an even bigger advantage. Not only will nothing get done, but the enemy will now know where you are. OOOOrrrrrrr you die too since you are late to the fight and you were outnumbered before you were even on your way to the fight.
There are obviously many more things to be said, but these are things that I see all of the time in my games. I say this as someone who had 9 out of 11 games with an afk last year. In the end, if we were good at the game, we would be in challenger. Just keep learning the game and having fun while doing it.
