Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Rely heavily on surprising the enemies with your high burst dmg early on and fight with team members to spread out your dmg taken.
About lvl 11 or so you should be able to be moving around the map with no problems helping with ganks and safely geting away or baiting the enemy team after doing so.
Remember to use the AOE stun early and often in team fights, and dont be afraid to take on an enemy with low HP as you will be healing for alot mid to late game.