1) there WILL be trolls,leavers,rage quitters,AFKers, and all that. if it happens, just stay calm and play the game out. if they're starting to blame you for stuff that you know you didnt do, just simply ignore them and play the game
2)use the new ping system to your advantage, it's much easier,faster and safer to call a "?" ping than to say "mia" in chat
3)try to find someone who will duo queue with you. this lowers the chance of one random on your team being a troll or AFK'er
4) play cautious if your opponent is agressive, your jungle will come down in time (if he is a good jungler).
5)learn to CS under towers, it's always a useful skill to have. 2 turret attacks +1 auto attack for the melee ones,and 1 turret and 2 auto attacks for the mage ones