My friend is diamond and told me how he passed gold.
If you're playing ADC and there's a huge minion wave top about to run into your tower and everyone else is mid, ignore top and go mid. ALWAYS (Except if you're Nasus, see below).
It sounds stupid, but you carry yourself out of elo hell by STICKING WITH YOUR TEAM. If you splitpush, they get 4v5'd and you lose. If you can get an ace mid, then push down an inhibitor, it's worth losing all that CS top (And sometimes you lose a tower).
Many bronze players don't know how to assess a fight. Many silver players (and gold players) don't know how to play a 4-1 splitpush. They just teamfight for no reason. So if you're top splitpushing and your team gets initiated on, your team WILL GO ALL-IN AND FIGHT A 4V5 because they're bad. I've sadly initiated plenty of 4v5 fights as Amumu (Bronze players also have bad map awareness, guilty as charged).
If you join your team and you get aced and enemy pushes an inhib and get 2 top towers, you were doomed from the get-go.
If you really belong in higher elo, stick with your team and show the enemy superior positioning and win the fight off that. So if both teams are mid and just dancing around, keep dancing until something happens. If everyone disperses, just go jungle or clear a lane or ward the jungle.
If your Tryndamere is clearing top while you're all mid, just disperse (NEVER FIGHT A 4V5). Retreat ping, etc.
Usually, low elo games aren't won off of mechanics, they're won off of "who has more players in the fight". Don't have less players.
If you really don't want to teamfight (seriously, they teamfight every 2 minutes), stick to Nasus
. This dog will just Q-Farm all day and splitpush until you win. Remember to buy wards so you can teleport to them (and to see ganks) and continue the splitpush. Spend the extra 250 gold on the upgraded yellow trinket. Your team will die. You may even be 1v3'd and die (You should be able to handle a 1v2).
But hopefully, the enemy can only push down an inner turret while you're bashing their inhib turret. And by the time they retreat to defend their base, you'll die (and it's okay!), but they lost a tower, an inhibitor, and 2 members of their team.
99% chance the enemy will group up mid again, raring for a teamfight, and you just need to TP to a ward and eat the rest of their base while your team tastes the brutal agony of a 4v5.
After you get like 600 stacks, you can probably solo an inhib tower without minions (And your ult, with Triforce, etc).
tl;dr: Stick with your team at any cost, except if you're Nasus, then splitpush until you reach gold.