analyze other songs. i found it pretty interresting to first only look at the lyrics of a song w/o knowing what the song sounds like. sometimes you think "how the hell is this supposed to be sung" - and its very interresting to see the way the singer worked it out. sometimes cut sentences into pieces. sometimes "swallowing" a few words.. think of a vocal line as a solo - you have no problem fitting a solo over a certain chordprogession, do you?