Tips for a beginner?

Learn the basics, like each champion's abilities, how to farm correctly, what to build with each champion, basic wave control, etc.
/Mute all (optional, but very useful if you care about your mental health lol)
Play a lot of games and watch a lot of League-related content.
And last but not least, if you're NOT playing competitively, try tohave fun, it's a game after all, this does not mean you have to play to lose tho, you can have fun and play to win.