Mark Twain and Truman had to write lying down.
Ernest Hemingway sharpened fifty or so pencils before he started.
Willa Cather had to read the Bible before writing.
Poet John Donne felt he should lie in a coffin before putting pen to paper, that’s a story in itself.
What’s your ritual? Personally, I have to have a cup of tea handy – just to hold, seldom drunk.