What to do to improve at yugioh (edison)

The steps :
Step 1 : find a deck and netdeck
Step 2 : don't touch the main deck build anymore, play A LOT (with intention) focus only on learning the game

...
Step 3 (way way in the future) : come back to perfect the main deck

Explanations :

The main message I want to pass, is in the step 2 : HAVING A PERFECT MAIN DECK BUILD IS THE LEAST IMPORTANT THING, BETTER GAMEPLAY IS THE MOST IMPORTANT PART.

When I say the deck does not matter, I mean, the perfect deck does not matter. If you go to a tournament with a Jaden yuki deck, expect to loose.
You need a competitive enough deck, this is why you should netdeck, if the deck topped a big yugioh event, that means it is competitive enough.
Going from an 90% perfect deck, to a 100% perfect ratio deck is not important.

This thought process I found it from the game League of Legends : in League of Legends you play a character that you can personalize through runes (changes before each game) and items (change during each game). Two coaches (HitTheLow and Coach curtis) recommand to ignore the personalization : stick to one rune page, and one item build path each and every game.

Because those personalization are meaningless if you don't know how to pilote your champion : a player who has not fully optimized his character runes/items but do lands 90% of his abilities will do Way More damage than a player that optimized his character but lands 50% of his ability.

The same can be said in yugioh : wether you play Upstart goblin or Legacy is not important if you don't assess your oponent cards well, and ran into a trap you could have played around.
Playing 2 or 3 Rykos is not important if you don't understand WHY you play them, when you play them, and when you side them out.

If a yugioh player skill was a pyramid, Core gameplay fundamentals are the layer below deckbuilding. Your skill level and knowledge with determin how you value each cards and ratios. A great example is Starlight road : aTrueHero cut it off because his knows how to play around it, and he knows how it feels when your opponent plays around it.

Here are the core skills that you should focus on this first :
-piloting correctly your deck (it's interactions and combos)
-the purpouse of each cards in your deck
-the interaction of your deck with the opponent's deck.
-yugioh fundamental skills

Small details :

-Side boards cards are the exception, the difference between a good and a perfect sideboard will impact your sets way more. Also sideboarding will make you work on a lot of fundamentals : learning you deck (what you can cut) and learning the opponent decks (what they dislike)

-If there is this card you really hate in your deck, or you really want to add in your deck, do it. Just don't go out of your way to test each and every tech options your deck has.

In my spare time, I am a volunteer facilitator for the game "Climat Fresk". Climat Fresk is a serious game which lets you learn about the climat change. Please try it, you will learn a lot of things thanks to it ! => https://climatefresk.org/