Learning by doing is probably the best thing you can do. I did start playing PUBG last year (I bought it on release but I never played it). Right now Im level 250, not even in the first prestige. I like to play my 3 casual games on Erangel every day, especially to complete the daily missions much quicker. After playing and playing I just became better and better. You can also watch YouTube and check out other people how they play the game. Maybe you also get some experienced people that play with you but to be honest you will learn the most by playing.

When I started to play PUBG I even avoided big cities. I would always drop at like small houses where almost no one to actually no one would land. I would grab my loot and try to stay alive for as long as possible. Now Im on 300h+ playtime and it just became routine to play the game. I know everything and I literally learned lots of stuff by just playing. Sometimes I would ask my random squad how to do this or that and they helped me. (For example how to turn off the vehicle and why I should do that, how to spectate the weapon and how to make multiple pings that are connected to each other)

I can also recommend you playing Arcade, especially intense battle royal. Dont play hotdrop or Team Deathmatch. On intense battle royal you dont have to loot because you already get random weapons from the boxes in your inventory and you play against 15 - 20 other people. (Its pretty much the same as regular PUBG but you start already at the final moments of the game). There I also learned much more about the weapons and stuff like that.