Making a living from writing books: what works, what doesn't

So the the Authors' Licensing and Collecting Society has done a survey, and found that the median average income for professional writers in 2013 - those who spend the majority of their time writing - is £11,000 a year, down from £15,450 in 2005. The number of writers who get all their income from writing is down from 40% to 11.5%. And I know anecdotally that advances are down by 30-60% compared to ten years ago: a typical £5-10,000 for a first novel from a big publisher in 2005 translates to more like £2-7,000 now, still paid in up to...