Posted 27 August 2006 - 08:02 AM
It depends on the kind of music you're writing and what kind of tone and mood the song you're writing has. Country, acoustic, folk, and rock-based writing has more of a tendency to go from lyrics to music whereas pop, dance, r&b, and hip-hop goes from music to lyrics.
If you're writing to a beat, generally speaking, I'd recommend just singing along to it with any random words that pop into mind until you find a melody that you think is suitable to use and then from there progress into writing lyrics based on a general theme or idea (i.e. "This is a happy love song," "This is an angry love song," "This is a song about ____ person and how much I ____ them."). Sometimes thinking of a title based on the beat itself can help you decide how you're going to approach writing lyrics.
If you're going from lyric to music then there's tons of approaches. You can start out as writing poetry or you can just randomly think up melodies with lyrics in your head (which is what I generally do).