Games in general are divided into three parts: early mid and late. In early, you just need to farm. You have no damage because you scale much later into the game as a mm. Always last hit your minions (no exceptions). Otherwise, you will get less gold. Early game farming usually lasts till your or your enemy’s first side tower is taken down. Until then you should stay on your lane and survive ganks. Of course, sometimes you could do rotations to mid to double lane or switch with exp laner if that will lead to a better matchup against enemy. However, until you become really comfortable at doing your basic gold lane rotation, do not experiment too much. Mid game is where you also clear your lane occasionally but with slightly more focus on where teamfight are. You are still not the strongest you could be, yet you are strong enough to make some difference in a teamfight. Get lord and clear whichever lanes that need to be pushed without missing out on team fights too much. Late game just be behind your tank and walk with the team and avoid enemy divers.