The primary principle behind the technique of linear perspective is that objects that are far away appear smaller than they really are. Linear perspective is a form of perspective in which parallel lines seem to meet at oneor more vanishing points. The first painter to use linear perspective was Polygonus, in 5th Century BC Greece.
Well. Start with why you want to be a marching band leader. what is your though as to why you want to be the leader of this marching band and maybe you find you have more than one reason and expand on that keep adding detail.