Bronze is essentially a test of your own skill.
The way to win in bronze is to abuse your lead by helping others.
Top: TP-gank bot and tank for your ADC (assuming you're a tank).
Mid: Roam. Roam, and keep roaming bot lane until the enemy either alt-F4's out of the game or they type in all chat "need a tent?". And keep doing it. If you are constantly putting pressure on enemy bot lane then your ADC will do better. It's much easier to roam if you start on baron-side because there's 2 pathways you can come from.
Jungle: Camping. Pretty self-explanatory. Don't leave botside for long. Although I wouldn't go jungle to carry yourself out of bronze because, from my own experience, all lanes will need help all the time and players just can't micromanage all of this at once at this ELO; jungle success comes from counterjungling and early kills/snowballing.
Support: You kind of just have to get good at this role. It's a lot different from any other one in that you don't have to worry about CS, which is a lot easier, but you do have to worry about positioning and wards. Practice some norms with META SUPPORTS ONLY because I guarantee if you go Teemo/annie/velkoz/any AP champion as a support you won't do it right at this ELO. Just play Soraka; she's a simple support with a lot of utility and healing.
The ADC and the jungler are the two roles that decide the game, every time (in bronze). If you're jungler is behind, you're immediately screwed. This is why invades are so common; incredibly high-risk high-reward that can win/lose a game. The ADC determines late game. If your ADC isn't fed but theirs is, you already lost.
If you don't play ADC/Jungle, then the best way to help is to help bot lane. Mid lane should be at bot whenever the enemy mid is dead/backed. If the jungler is being chased, you drop EVERYTHING and go help because that one kill can decide the game. Especially when you factor in the Bronze Tilt effect (over literally nothing).
Finally, some good bans are Caitlyn, Master Yi, Yasuo (probably the only non-ADC/jungle that can decide the game), Fizz, and then whatever counters you in lane. I see a Master Yi virtually every game and he's guaranteed to hit his late game in this ELO. I've never seen a Yi that hasn't. And since bronze games are drawn out to 30+ minutes because of lack of objective focus, it's even more likely to happen.
I'm B4 myself; what do you main? I can try to help you but I'm probably not the best person to do so.