Asking for YGO Veteran Advice

I've been a casual YGO player for about a year now. I've been having fun in casual matches in Gold/Platinum and never really got into Diamond because the focus was on having fun. However, with each DC event, I get the feeling that I should focus on competitive and be a better player.

I'll only play 1 meta deck and I have enough decks. I'm asking for advice on how to improve because I feel like I have a lot to learn but I don't even know what to learn. Example, I don't know what interactions I should make or predict opponent's moves.