Guidance with playing Clash royale

Hello, community! I've been playing Clash of Clans since 2013, and now that I've maxed everything out there, I thought, why not give Clash Royale a try? I started playing two days ago and could use some guidance, tips, and tricks for beginners. I'd also like recommendations for beginner-friendly decks and advice on what to upgrade first and what not to upgrade. Additionally, if there are any clans accepting new members, I'd love to join!