If they knew how to properly prioritize and take objectives, then they wouldn't be in Bronze or Silver.
Honestly, all you need to hit Gold is decent mechanics, game knowledge, and decision-making. You don't need to excel, but that's honestly enough to hit Gold or Platinum.
Don't believe me? During two of my placement games, two Platinum junglers--Master Yi (me) and Nidalee (an ally)--died during our first clear to a buff camp without the enemy jungler interfering.
We still managed to recover and carry our teams.
Anyways, if you want to climb through the lower divisions, I would recommend playing two types of champions.
The first would be tanks and fighters with good CC (i.e. Volibear, Gragas, Amumu, Nasus, Nautilus, Irelia). Durablity and crowd-control is extremely useful for teamfighting and are commonly lacking on lower-ELO teams.
Honestly, too many people insist on playing carry champions like Master Yi, Tryndamere and Vayne, leaving teams too damage-focused and lacking utility or a decent tank. It's honestly quite easy to carry games as durable tanks and fighters since many people don't know how to properly kite or focus them.
The second would be seige champions. In my experience, people will constantly group around objectives in Silver; both teams will converge on an objectives and spend a couple minutes facing off against one another until someone gets caught. Champions who can poke or engage/disengage during these periods (i.e. Varus, Ziggs, Gragas, Corki, Morgana, Lux) work extremely well in these situations.