A friend sent this link around, and I can’t recommend it enough. Ten tips on writing a novel from some of the best contemporary novelists around. (also useful principles for any kind of writing really).
The only one to add is this one, which is complete gold, from Ann Le Motte:
“The only way I can get
anything written at all is to write really, really shitty first drafts. If one
of my characters wants to say ‘hey there Mr Poopy Pants’, then I let him.”