Focus on positioning and farm. These are some key fundamentals that you will need to get better. I always try to shoot for 100 cs by the 15 minute mark in lane unless support.
I wouldn't recommed jungle at a lower elo unless your just an amazing jungler, because its not a role you can really carry a game from in my eyes. I know i will get flamed foro that statement. But you will have those teams at bronze level that you just can't do anything for from the jungle.
I would focus on ADC, mid and top and learn a few champs very well. I know this advice doesn't translate to everyone, but coming from someone clawing thier way out from rock bottom, its what i've found to yeild the most results. I've gone from bV to bII in about a week.