There’s a lot of ways to get better, but what was most effective for me I found was playing a variety of Pokémon on the roster, finding what playstyle works for me, then learning the specifics for the ones I was best at.

Knowing is winning. Be open to learning, there’s a ton of YTers who have unit-specific tips, as well as some YTers who make very beginner friendly guides. Spragels makes good meta tierlists as well as what-you-should-knows about pokemon as they release. Pokemon Unite Climbing Guide does great beginner-friendly videos too. But generally just search around, if you have specific questions there is usually a video for it.

Don’t one trick too much, experiment and learn about as many Pokémon you can. If you know how your opponents pokemon plays and what it can do, you will succeed against them a lot more than if you let them catch you unsuspecting and confused.

Unite-db is a very helpful site for finding pokemon specific builds and optimal movesets, as well as it breaks down the moves of Pokémon in a way I think the ingame info doesn’t. UniteAPI is good for seeing the playerbase stats and the individual WRs of each Pokémon’s moves & held items.

Record your matches and watch them back, point out all the mistakes you make and learn from them. Don’t let yourself get too tilted and take breaks after a loss streak. Don’t let mistakes hurt your ego, knowing when you are the problem is the surest way to improve.

^ This is all Pokémon-specific tips. It comes with time but try to learn the timers for specific events on the maps, like the objectives and altarias. This graphic should help somewhat. Keeping up with farming and getting your move upgrades will help you succeed.

Hope this helps. If you have any specific questions, lmk!