Before you even get into a game you should be considering which champion you are going to play based on the match up. Don't play assassins into a tanky team i.e. Shaco, Evelynn, Shadow Assassin Kayn, Qiyana, Talon versus Cho'Gath, Sion, Shen, etc. Make sure to watch as the enemy team picks to see what jungler is best. If you don't know how to play a champion there's no harm in learning a new one in a normal game. Also make sure to watch what side you're starting on. Blue side will say first pick above the very first person in champion select. If you're on the blue side of map your leash will be on red buff. If that's not what you need initially and you're a jungler that needs a leash communicate it with your top laner in the champion select screen to make sure they leash because it is not their responsibility, if you say no try going a different pick with good early clear, i.e. Shaco, Yi, Warwick.