A few posts ago I said I'd buy some pencil crayons. Colour really helps (and these days I've a camera on my phone so even if the results are poor I've still got the original pencil sketches: see earlier post)
I've tacked these scribbles above my writing desk. I try to avoid lunar-barren walls as I write. I don't like the wall in front of me to resemble the blank in my head when I get stuck.