I would just say don't give up. You'll eventually get where you're supposed to be no matter how your teammates preform.
You're going to have tons of frustrating moments where you lost promos because of a disconnect or a teammate feeding/refusing to group.
You're gonna be at 99 LP after a 50 minute game you worked so hard to win.
Etc.
Don't let that stuff tilt you.
I don't know if I can give you any gameplay advice other than the basics. I'm a Gold support main. I climbed late last year as support, and this year I just recently got into Gold 5 after an early start. However I did get to Gold playing top lane in Season 5 fairly quickly.
I don't think Bronze 4 is a death sentence. You can make it to at least Silver 3. I've never been to Bronze, but occasionally I'll get Bronze players in my normal games. There isn't really a big difference skill wise. What I tend to notice is people have more game knowledge.
They know they need to stick to a small pool of champions, and learn them well. Do not play 8-12 different champions in ranked. The fastest way to climb is to become a one trick, but if your main is someone like Yasuo, then you need to also realize he gets banned a lot. It's good to have like 2-3 other champions you can play comfortably.
My next tip to you would be to learn the support role because you're eventually going to get autofilled. Being a basic functioning support isn't difficult. You may not make any flashy plays, and you won't always save your carries from a close call that they got themselves into, but you can still do a lot for the team on a basic level.
As a support main I'm always paying attention to power spikes. You should work towards having a general idea of what champions do, and how you can outplay them. This pretty much just comes from experience. You need to play the game more to understand champion interactions.
As a final tip I would also say know your limitations. You can't play too safely at Bronze and low Silver I noticed. Sometimes people will just give you kills by diving you, or coming at you with very little HP after you've been farming well.
Don't overstay if you're fed ever. The bounty on your head will allow players to come back. My friends in Silver never pay attention to stuff like that, and I'm sure it's worse in Bronze. In fact, don't overstay period, but I know that's easier said than done.