Supposedly the best advice would be to drop your loser friends and get friends that are winners (/s).

If you can play with a regular team that you synergize well with, it'd probably help quite a bit. I mean, you should still play with your friends even if they're not great and maybe lose a few games every now and then, but you could also join a random group that wants to rank up and be better at the game, hopefully like-minded and at the same expertise level as you. Even having one online stranger to play with regularly makes a big difference.

However, to just depend on solo queue, you'd probably have to have to ask more detailed questions about your own gameplay/thought process and have someone analyse how you play (like some sort of game mentorship similar to CS:GO's 'adopt a silver' community). It would be really hard to control any external factors beyond yourself.

If you insist on the solo thing, or just want to get better in general, maybe watch videos on how other people play heroes you play (not just 'teh pros', but any player who seems to know what they're doing). Note how they communicate in game and how they turn that information into their favor. Or note how well they manage internal rifts and conflicts that inevitably occur. I find that many game losses back in Plat/Diamond+ are due to toxicity, crushed team morale (which leads to in-game trolling), and bad communication more than it is about skill/ability.