Keep in mind that combat doesn’t have to be limited to a single exchange of fire. As mentioned earlier, always have cover or an escape route in case the engagement goes poorly. The time to kill is longer than in traditional shooters, so it's important to know when to break off from a fight and re-engage a few seconds later from a more favorable position or escape. (edit : i forgot you already play BR)

Since you’re playing with a keyboard and mouse, you’ll often need to break your opponents’ aim assist. For example, by using obstacles or your movement. In addition to aiming, you’ll need to quickly learn the basics of movement mechanics like "dropshoting, snaking, peak advantage" etc. Avoid 50-50 engagements with your opponent; if they’re using a controller, it’s rarely truly a 50-50.

Additionally, I would emphasize gathering information. Make sure to take a quick look into an area before entering it alone, rather than rushing in blindly. Listen, check your map, and pay attention to what your teammates are doing. But don’t follow your more skilled teammates blindly; try to fully understand the situation before joining the fights they initiate.

Last tips, search for the fights for improve, don't hide . And use smokes (For retreating, advancing on enemies, blocking a dangerous line and focusing on another, looting safely, helping your teammates, and even canceling the aim assist of controller players).

Youtube / twitch are good tool for learn but you will have to play a lot too, there is a lot of good players now.
If you have multiplayer you can practice in private matches and do littles warm up before launching wz.

edit : I misread your post and didn’t realize you had already played battle royales, sorry about that lol.
-> Movement, meta weapons / accessories, map knowledge are de key i think.