7) Not Prioritizing Towers and Inhibitors

No, getting the dragon is not more important than snagging that open turret. No, a massive team effort to down Baron is not going to help as much as a push that takes out two of the enemy inhibitors. Too many times you see noobish players hang back and hit creeps while their lane opponent is taking their time shopping for boots. Destroying towers is what wins games, and thus they need to be high priority targets at all times.

Always go for the tower