okay, here's the thing. There are often times a particular structure to songs. And if there isn't, it'll be a mess. but SOMETIMES, you WANt a mess. It all depends on what the song needs. How you want the song to make someone feel, or yourself feel. It's all about emotion. Just do what feels right. A lot of the times there are no particular "verses" or "chorus"...if you've ever listened to a Tool song, one would realize this. My personal theory is that a song should "build" and then climax. An example to this are the rock GOD's pink floyd. Some of their songs go for 15 mins, and there's no particular chorus or verse arrangement, just an overall theme.

Anyway, don't submit yourself to the average radio mold of verse, chorus, verse, chorus, bridge, ect. Just do what feels right for that particular peice.