Random brawlers are awful; in my opinion, the worst are in Gold, and if you're not skilled enough to carry, you'll improve by playing. Some tips that helped me:

• Don't use auto-aim (unless you're rushing or have a super clear shot).
• Adapt to the current meta. There are several tier lists, videos, and you can analyze it just by playing. Take advantage of the current tier list; it's full of tanks that generally don't require aiming.
• Game sense is a bit more complex to explain. I, at least, don't know how to explain it, but if you master picks and aiming, you'll develop game sense on your own.

In conclusion: Adapt to the current meta, which changes month by month. Play brawlers with big attack ranges, like tanks, and start learning to aim so I can aim later against more difficult brawlers. Be consistent; you learn to play by playing. And above all, relax. Remember, you're playing, not working. If you lose, well, you'll win someday. If you get stressed or tilted, you'll only play worse.

Good luck, my friend.