LoL is a game in which you have to collect a lot of knowledge to be strong (cooldown, damage, objects, etc …). For this reason, there is no guide retracing the entire LoL and this explains that many players do not see the difference in skill between a platinum and a bronze. This is also why you can not find a “miracle recipe for improvement”. This is a miracle recipe or at least the list of ingredients in this recipe. I’m not going to teach you what exactly needs to be done at stake, but how to approach it to be better overall.
This guide can be used by everyone, but only the most motivated can really exploit it. Not all players are equal: not all of them have the same potential, the same basic talent, the same experience of PvP, MOBAs in general or even micro. But if everyone does not leave, everyone can finish it. As I said before, LoL is a game that requires knowledge: if not everyone is able to swim the butterfly, everyone has the ability to memorize information and store it in memory. It will take more or less time depending on the players, but it is within the reach of everyone, still needs to (really) want to become better. To play better, elo boosters are recommended.
I talked about motivation, it goes with the investment. You will not get better by playing 2 games in the week. If you play once every 10 years, but want to improve, the first step is to play more. 90% of the players are below Platinum: reaching this level is relatively easy, but for those who would like to go further, the investment of time can (must) be optimized (if you do not want to become a no-life or lose time not to learn). To invest in LoL is to stop thinking of it as a short-term distraction (as would be another lambda game for you) and to start thinking of it as a discipline in its own right.