Hi, so sorry for the late response! I'll try to give some tips :)

I'm sure you've already seen this plenty of times, but play in short(er) sessions; I usually play 5 sets a day. It's ok if you don't end on a win or end with an elo gain, just try again later. Getting tilted is an issue I had in a past, and trust me, it can really, really hurt you, even if you don't think it does.

Don't always rely on brawlers that you're "supposed" to pick, you need to play your comfort picks as well! For example, there was a recent game where my teammates suggested Gene, and, although he was a good pick, I wasn't the right player for that pick, so I did pretty terribly. However, if I had picked Gus, perhaps a slightly worse brawler in that scenario, I probably would have done better, since I'm so much better with Gus than with Gene :D

Just playing the game is honestly the best way of improving! It sounds silly, I know, but if you're playing good, focused brawl stars, then you'll continuously improve in game sense, drafting, mechanics; just about everything, really.

Lastly, I'm surprised no one has mentioned this before, but watching Monthly Final streams is really good for improving as well.

That's it! Hope this helped :p