I make a skeleton until I get to the chorus, then I build up whatever I'm in the mood to build, which almost always is the chorus, then verse, then bridge. Then, I make a copy of the song and paste it after the first chorus and then make differences to the second half (adding a solo, atmospheric change, or whatever) At the very end I decorate the song with whatever little frills or sound effects I want to add. I'm a huge noob at this though, so there's probably a better way at doing it