Here are a couple of things that I've picked up over the years.
Maybe this is just me, but I think you need a good notebook to write in, something that is a pleasure to open. I discovered Moleskine notebooks last year and I am now officially addicted to them. They are the perfect notebook, the right size, nice weight, wonderful paper to write on, even the lines are spaced the perfect distance and the off white paper is that much easier on the eyes. I love them. They are expensive,but I think worth it.
Something else I searched for for a long time was the perfect pencil. I've been drawing for as long as I can remember, did a year in art college, four years studying animation and I simply always drew. But I could never find a pencil I loved. Then, at a masterclass with disney animator Glenn Keane he shared with us what pencil he uses. The Sanford Ebony Pencil...
I love this pencil, even more then I love my Moleskines, if I had to choose, I'm sorry Moleskine, it'd be the pencil... but luckily I don't have to choose and together they form a perfect partnership, like Fred and Ginger, Tracy and Hepburn, Laurel and Hardy. They are a great pencil to draw with. They are round, smooth and slightly narrower then other pencils. They have a hard wide lead that creates a smooth dark line with perfect consistency, perfect for finite detail, dark broad strokes or equally light and heavy shading. For my money the best pencils around.
It's something I always tried to find out about, what other writers and artist use, so hopefully I can pass it on to some other budding storyboarder!