I'm beginning with my all-time favourite piece of writing advice. I like it so much, I have it pinned up on the wall of my study. It was written by JD Salinger, in his novella Seymour: an Introduction.
"If only you'd remember before ever you sit down to write that you've been a reader long before you were ever a writer. You simply fix that fact in your mind, then sit very still and ask yourself, as a reader, what piece of writing in all the world would you most want to read if you had your heart's choice? The next step is terrible, but so simple I can hardly believe it as I write it. You just sit down shamelessly and write the thing yourself."