For song writers struggling to make those musical sketches and random ideas for riffs into a finished song, think about the form the song should take.
I love the suggestion, in this blog post, about mapping songs you like and then using the knowledge you gain from that exercise to make a map of your own new song. This is how you begin to see song form and how to create it.
I also love the idea of using the verses for situations and the choruses to tell the audience how to feel about it (or how you feel about it). This blog site and the e-books that are available from it (which I have and paid honest, good money for) are excellent song writing resources.