Remember in english class how you were told to keep your essays on-topic? They said to come up with a thesis, and everything in the essay had to somehow support or build up to it. You weren’t supposed to put in lots of “padding” or go off on a tangent. Well, believe it or not, the same concept applies to music production.
Like a strong essay, your song should grab people from the beginning and make them want to stick with it until the end to see how you resolve the “question.” The intensity of the song has to be constantly increasing through contrast and changes in instrumentation, tone, and dynamics.