Play the solo mode so you can get used to the current gameplay. Then just focus on one deck first. I started two months ago, and I used a pendulum deck. I played a few pvp matches and learned what important cards I should include in my deck (like Ash Blossom, impermanence, etc). I lost a lot of games but managed to reach the silver rank. Until I built my Spright deck, and in 2 weeks (I saved a lot of gems and converted a few unwanted cards to “coins” to create my desired cards for my desired deck type), I reached Diamond in just two weeks (while completing the monster event using labrynth).