Yo - g3 here. I was stuck in s3-s5 for and only dropping elo for half of spring split. Didn't matter that I was getting camped 2v1 top for 90% of games and either STILL winning or at least going even in lane pretty much every game. My team still fed hard enough that any lead I got was overshadowed. Had 2 weeks where 9/10 games or so were auto-losses. Didn't matter if I stopped for 2 days to avoid playing when extremely tilted or not; soon as I played the next game, it was like these auto-loss teammates just followed me and were on my team every game. Focusing on them doesn't help. Contrary to what people say - often people who elo shame because ("i'm diamond and you are trash gold" or "I'm gold and you are a retarded silver 5; you know nothing") it's the only way they feel good about themselves - other people CAN hold you back. Not permanently, but it can take basically a full season to reach your proper elo.
On my climb from b3-g3 I have learned several things this year. P.S. I was g5 last year - peaked g4 before falling back to g5 because that WAS the elo I belonged at. One thing I learned is to focus on learning a few champs very well for each role you play. Once you REALLY know how to play them to perfection - at least at the elo you want to reach - you can start adding a few more but keep fresh on your mains for the role too or you will lose some edge. Pay attention to the micro and the macro. How could I have: won that trade I just lost, survived that gank or even turned it around, pressured the map better, focused differently in the teamfight to better protect teammates or kill priority targets faster? What combo's can my champ do and when should I do each one? Sometimes this is more a matter of figuring out your opponent's skill level and playstyle; if they play super passive or too agro or whatever to let you do your best bread-n-butter combo, what new/other combo can you do instead to punish their playstyle? Do you freeze the wave and build a huge cs and xp lead or hard shove? Do you set up a tower dive, look to land some poke damage while they farm under tower, or go roam? Think about WHY you are doing EVERYTHING.
If your laner(s) go mia, don't just ping your lane; ping on top of your teammates so they know your laner(s) might be headed there. This is low elo - once the first tower in bot lane falls, it's time to 3 or 4 man group up and rotate pressure between mid and bot. If your bot lane lost and you just sit bot, you will either overextend for farm and keep dying and falling further behind while the enemy picks up more farm, objectives, and kills on you for overextending bot. If you group with your midlaner and maybe jungler too, you are harder to punish for being behind and for SMALL mistakes. Similarly, if you are ahead bot, shoving the enemy tier 2 with no wards in the enemy jungle or minimal warding invites the enemy to 4v2 or 5v2 you and punish your lead while getting the enemy bot lane time to catch back up. Better to take that lead mid and force the enemy bot duo to answer your pressure around the map. If mid has too much waveclear, go top instead and get that and the rift herald if it's up. Translate your lead to OTHER lanes. Learn when it is best to force teamfights, to skirmish or duel instead of teamfight, to stall the game. Ping, chat a quick plan or 2 options to your teammates (before you get in a tense standoff or battle) so they have some GOOD ideas of what to do in their heads. Giving options can help some people be more willing to listen to good ideas because no one likes to listen to a good shotcall unless THEY made it; giving options means THEY made a good shotcall. Doesn't always work, but it's worth a try. Giving ideas like "focus their mid and jungler first in teamfights" can help your team come out on top. Remind people of the basics if they have forgotten several times in recent fights - like "don't cluster together for their aoe burst guys". Sometimes people get pissed off and harass or flame you for this, but if they are not doing it, it is worth reminding them.
Map pressure and smart objective trades and forces goes a long way. You behind and the enemy team has baron or is just splitpushing? Set up a huge minion wave push in the 3rd lane to distract/tempt the enemy team so they send someone back to clear it before it grabs a tower. Now you can force a 5v4 when behind instead of worrying about the splitpush killing your base while you try to stop the rest of their team. They going for dragon or baron and your team didn't listen for the last 2.5 min and ward anywhere around the objective? If they are ahead, facechecking could be fatal. Maybe you know where some of them are, or even all of them but you know you can't win a 5v5 yet because your team is too behind. Can you turn to the opposite objective (drag or baron) and sneak it away asap while the other team grabs the opposite objective? It's one of the most overlooked and favorite plays I like to do if my team will listen. High elo, you couldn't get away with this most games, but this isn't high elo and you often can. Predict where and what the enemy team is going for and move accordingly. Do you hard engage and punish it, contest and stall it, avoid it at all costs to not give them a game ending fight, trade objectives? Learn that stuff and you will climb some even if your mechanics only match what your current elo is.
Never give up. Improve yourself, work on communicating with team better and learning to help/manipulate them into making smarter TEAM decisions. And if people aren't quick to listen to good shotcalls - or even if they are - be extra sure to point out GOOD plays and shotcalls by teammates. I mean if you are more likely to listen to a decent shotcall by a teammate because he/she listened to one you made awhile back and said "nice call" or something like that; why wouldn't your teammates be the same way? If you are meant to climb, you will eventually get there as long as you stick with it. You can only get inting feeders and trolls regularly for so many games in a row. Eventually you will get that gap you need and climb to the next elo and run into... more int feeders, trolls, people who are boosted beyond belief and should be in wood 5, great players, and average players who are right where they are supposed to be. Sadly I have seen some people with better mechanics or better micro and macro intelligence in bronze than some that I have seen in silver or gold. The mechanics generally get better as you climb, but not for everyone. And the horrible decision-making, lack of warding, 1v5 mentality, and other horrible traits remain. That said, there are still those magical moments when you get not just a good team, but a fun team to play with who work together well and you wish you could just be 5 man pre-made in solo queue for rest of the season.