Before we do anything,we need to make a plan for it.Then we can do things fast and effectively.Making a good use of time means spending time in doing something good or useful instead of something useless or unnecessary.So I believe,firstly,when we spend our time on something such like homework or reading,we need to completely focus our attention on them which is able to save our time as much as possible.Then we can use the time we save to do something interesting such as taking exercise,travelling and making friends.Them,we can really make good use of our time.