When my band writes songs, either me or the other guitarist will start playing some riff we came up with, then the drummer will start to come in with something, and the whole time the bass player will stare at us for a while trying to figure out what we're play, make an attempt, stop, stare some more, then we'll stop and show him what to play...lol. Or, the drummer will just start banging away, and we'll just pull something out of our ares's and hope for the best. Usually our singer already has a bunch of lyrics she's wrote and sh goes through them 'till she finds one that fits. Then we work at structuring the song. Then we record the song and work out any details that need attention. BAM! we've got a new song :D