a ruled notebook from WHSmiths, and a Bic biro pen.
I'm serious.
I have tonnes of the things lying around. Most of the contents now are rubbish, and will never see the light of day in a song, but in terms of getting creative, it's really the best way, IMHO.
I've tried methods from other people, but it leaves you with a problem that things might never actually sound how you really feel you want them to be.
BUT - don't limit the contents of your 'songwriting' books to lyrics. draw pictures. write thoughts. write down the first thing that comes to your head.
You'll find some pretty thoughtful songs coming through eventually. It's pretty hard for me to sit down and thing 'i'm gonna write a love song now' or 'i'm gonna write a rock classic' cos it just never seems to work like that.
Beautiful images do come, but in your own time. I don't think you can sit down and just consciously write a beautiful song at will.
But that's just my way. I'm sure many will disagree.
The thing that bugs me with tutorial books for songwriting/guitar playing, etc, is that I've never ever heard of the author. I don't dispute that they might be good at what they do, but they haven't put it to practice. Now if Lennon & McCartney had written a book on songwriting, i might have bought it, because time after time they just churned out classics.
I hope you get my point.