To elaborate a bit on my post, I went so far as to change up my champion pool to mechanically much simpler champs (Darius helped me climb from Silver 4/5 to Silver 2, Garen from Silver 2/3 to Silver 1, and WW for that last stretch into gold).
When you play simple champions you notice how much of an impact every missed skillshot has. You notice what's going on around the map because you aren't focused on winning trades or mechanically outplaying anyone. You notice when you're behind in CS more and when/why you get behind. You notice when you're overextended without vision more and why you were ganked. You notice what the team is doing that allowed the enemy team to send five top and murder you. Etc.
Also you want to go out and look at all the tools out there available for you to learn what is good. You need to find winrates for champions in various roles in your ELO. Op.gg provides a very good overview of champion statistics for each ranked ELO and can be narrowed down by server. Champion.gg provides information on where people are typically taking a champion and how people are building them/what the highest winrate build is on a champion including runes and masteries. Probuilds.net shows you how pros have thought about building certain champions and the deviations they make in various situations (or if there is a solid core build that keeps repeating) and also gives info for runes/masteries. You can also follow the summonerschool subreddit to get info on various champions and how to play them. For example, I picked up WW jungle after someone linked a guide by a master player there and was easily able to pick up the champion and build him effectively based on the info in that guide. There are a lot of guide sites and even more guides, so finding one that is actually good can be difficult.
Once you learn which champions to avoid (i.e. 42% winrate on Taliyah means you have to be MUCH better than the average Taliyah player to get a positive winrate on her, vs 55% winrate on Amumu means that even if you are below average on him you can still maintain a positive win ratio and climb) and how to build your champs, you start looking at really basic shit like CS and warding. Do you buy a pink ward every game? Do you upgrade your trinket? If not is yellow trinket more valuable for some reason? I find in silver people still don't ward so having extra wards from yellow trinket is really good unless you're a squishy carry that will die if you facecheck. I play Ashe though so with hawkshot I keep yellow trinket anyway for additional ward coverage.
Even things like how you are using chat or how you respond to a difficult game can matter. I found as WW I could carry some pretty ratchet games and get my team a win even if playing from pretty far behind. If you surrender those games because you don't feel like trying then you probably won't climb, or it will take much longer. I have a rule that I never vote yes to a surrender vote because it instills in me that I always have to play as if there's a possibility that my team can win. This forces me to play at the absolute best of my abilities every game and question the things I did wrong in fights so that I can play better when my team is not 0-30.
One big thing is to focus on objectives. Practice never chasing the low health enemies if there is something to take (tower, baron, dragon, inhib, buff, enemy jungle camp, etc.). When you chase you tend to end up face checking the enemy team and lose the kill + feed more kills to the enemy. Even if you can only take gromp and wolf camps that's still guaranteed gold for you and gold/xp denied to the enemy team. Only chase if you can reasonably expect to catch the enemy before they get dangerously into their home field.
A big one people in Silver have trouble with is that they don't play safe when behind. They still try to build damage, when they would benefit more from just getting a tank item or an abyssal (ADC obviously doesn't have this option which is one reason it can be difficult to play from behind as an ADC, you just have to be more aware of which CS you are going for or play someone like Ashe who can duel the enemy carry from behind). Don't be afraid to rush an abyssal if you're mid or some armor/MR+health item if you are top/jungle. I find that the damage you do with a suboptimal build almost always exceeds the damage you do when you are dead in 0.3 seconds and the enemy laner is up 5 kills.
Also don't look for the one mistake that "cost the game". As Malcolm Gladwell pointed out in Outliers, one single mistake never results in a catastrophic failure. It's always the combination of multiple small failures that causes a catastrophic failure to occur. For example, a plane crash might be caused because a pilot has been flying nonstop for 14+ hours and is tired, there are poor weather conditions, and some of the electronics are malfunctioning. If any one of these things was not occurring then the plane wouldn't crash, but the combination of all three at once causes it to happen. Similarly, in your ranked games a lack of jungle pressure resulting in lost lanes resulting in lost objectives might have snowballed the game to the point where one player getting caught out cost the game. If any of those prior events hadn't occurred then either that player wouldn't have had the chance to get caught out, or getting caught wouldn't have had such dire consequences. It could be something as small as one ADC farming enough for BFsword while the other had to recall with just enough for pickaxe + boots that causes a game to snowball out of control.
Well this is all very generic advice, but if you want to feel free to post some replays in here and I can take a look for you and help you try and figure out what is holding you back. Looking at your op.gg I can see your CS was low in that Fizz game (120 when at 25 minutes having around 200 would be preferable). It also looks like your champion pool is quite broad for someone still in low ELO. I'd stick to 1-2 main champions. For example you have a combined score of 3-8 from trying to pick up Azir and Fizz recently. Your attempts to play Viktor have netted you a 5-13 record. Whereas if you stuck with your best champions Ezreal, Lissandra, and Graves you'd not only have avoided those losses but also would probably have benefited from your 60+% winrates on them. Eventually those winrates will go down as you hit your skill cap, but it's much easier to figure out your mistakes when you're at your cap vs when you are just trying to learn a new champion.