All I can say bud, is think of it as " I can't carry alone, I need my team and they need me. " You can't be a soloq hero. As much as anyone wants to say " I carried myself out of Bronze playing x champion," They can't. Their team helped them.
All in all, coming from someone who is struggling in Bronze, I can say the following is helping me out:
Play what you know! Don't decide. " Oh I know Sej is an OP jungler, but I don't know how to play her! " Just stick to what you know, trust me. In time, you'll be basing yourself of what you play the most.
That comes to my next point: I'll use an example for this one. I -LOVE- Malz. Have every skin. Played him since S2. By now, I know all the ins and outs of Malz. If someone instalocks Malz or takes him, I know how to beat him.
If someone picks a champion YOU know VERY WELL, beat 'em with that knowledge. BUT DON'T PLAY WHAT YOU DON'T KNOW. I've seen people say " Oh I know how to beat Riven! Garen!" and then lose because of what they don't know.
Along with those two things, are the common " Don't get greedy, CS if you're behind. "
Another thing, if you're champion is a HEAVY push laner, try roaming to help the other lanes while your lane is shoved. Your team will appreciate your help. =^)