League of Legends (LoL) Question: How can I be better rank ?

In my experience, the hardest climbs happened whenever I picked up a meta/OP champion that I hadn't played before (or that I hadn't played for a long while, or that I hadn't played in the position/playstyle/build it's being OP/meta). You have to play that champion for a while in normals until you're familiar with its mechanics and actually enjoy playing the playstyle that is strongest on it. This also means actually making some research on what to do early/mid/late game and its powerspikes.

My guess on why it works:
- You polish whatever mechanics are core to that champion/playstyle. For example, if you pick up Nasus and play it for a while you'll learn how to farm and play passively. Then whenever you play someone else you'll be in a position to play passively and farm properly if you're in an unfavorable matchup.
- You might find a champion that plays in a way that feels more natural to you.
- If you already have a main, you will learn a lot about the enemy champions, making those matchups more easy.

Of course this won't work if you have already rotated through every champion you're interested in playing, that's why I also included a bunch of general tips.

I classified some of these as Gold/Plat tips, but all of them are valid for all elos. It's just that in my experience every elo has its most common shortcomings, so focusing on them should be an easier way to get better, faster. I think the average Silver/Bronze player should focus more on mechanics and general strategy than powerspikes and different game stages (they're also often better off just playing smartly with late game champions).

• Learn from every mistake YOU make. Rule of thumb: whenever you die, there's something you could have done better. Rule of thumb #2: the mistakes your allies make are of no use to your learning, unless those are mistakes you recognise you could have made. At any rate, if you're criticising your allies instead of learning from them or polishing your play you're wasting your time.
  
  
• Buy pink wards whenever you can. Being right about the gold to finish big items might be an exception ONLY if that item could make the difference in your lane matchup (see: powerspikes). If you aren't buying more than the average for a Gold/Plat team, you're not buying enough.
  
  
• Gold/Plat tip: Check the map every 10 or so seconds. You should know why this is important. The thing is, making it a habit will make you notably better than the average Gold/Plat player. Just looking where everyone is and who is missing/dead should be enough.
  
  
• Gold/Plat tip: Understand your champion's and the enemy's powerspikes. Powerspikes are moments in the game where you get a big boost to damage/survivability/utility. The most common powerspikes are:
  
  - The first level of every ability. Because every new ability adds way more power than any of their subsequent levels. This is why the first team to get level 2 in any lane can abuse that advantage to bully their enemy.
  
  - The levels when you upgrade your ultimate, especially the first point of it (see above). Notice some champions (like Pantheon, Shen, Ryze) have team-oriented ultimates, which means they have to abuse those powerspikes outside their lanes, and champions with 1v1 ultimates (like Fiora, Darius, Garen) will probably outscale them in 1v1 fights at this level. Some other champions don't have ultimate abilities or start with one point on them at level 1, so this powerspikes are weaker on them or work differently.
  
  - The last level of the first basic ability you maximize. This one is harder to explain, since it involves understanding that every champion is balanced with a power budget in mind. tl;dr this is why most champions max an ability by level 9, level 10 at most. The other two abilities often have smaller powerspikes. I can dive deeper in this if you don't get it, because it's long to explain.
  
  - Whenever you finish a big item. Finishing a big item always adds something unique, be it in the form of raw damage or in some active/passive that can only be exploited in certain scenarios. Some items make bigger powerspikes in some champions and sometimes the powerspike comes after you have a combination of certain items.
  
  *Notice that powerspikes amplify each other. So if you back at level 9 with Kog'Maw, having maxed Bio-Arcane Barrage, to buy a Guinsoo's Rageblade and your support Janna also got to level 9 with a maxed Eye Of The Storm you'll go back to lane having the potential to start winning fights you were losing.
  
  You have to aim to knowing every single major powerspike within your intended build in your champion to understand the tradeoffs you're making when maxing one ability or the other and buying one item before the others. Some champions will have very clear powerspikes, even from minor items (an Irelia can make a huge powerspike out of Sheen and Phage), while others will be less clear but more constant. In my experience, getting your ultimate, maxing your first ability and some combination of items within any coherent build (i.e. that has any important interaction with your champion or with the enemy) are always powerspikes.
  
  
• Gold/Plat tip: Understand your champion's role in every stage of the game. Some champions shine in the early game and need to snowball that advantage to win before the enemy starts outscaling them. Some others are hypercarries that can destroy the entire enemy team after some late game powerspike. Some others have a decent early game that transitions into a great mid game for the mid game teamfights, but they don't carry too hard if they reach the late game. Knowing this will guide how you should play during each stage of the game (Gold/Plat is IMO where people have to learn how to close games early if they have an early/mid game focused team).