I just came across this recording of one of the London Book Fair sessions, entitled How to Get a Literary Agent. It’s really worth a watch if you’re aiming at a career as a writer but you don’t already work in publishing.
A lot of it is familiar to tired old hacks such as myself because it applies to any publishing project. But if you’re not used to thinking about the entire product – for instance considering the life cycle from manuscript to sales/marketing – and have mainly been focused on the writing to date you should watch. Remember, publishing is a business. There’s a point about 17-18mins in where they mention a rejection along the lines of:
Best book I’ve read in 6 months. Loved it. Can’t sell it.