My wife and daughter are both writers, and swere by the writers and artist yearbook, writers handbook both of which are available in bookshops or on the net, but you may also get information from two retail magazines, writers forum and writing. Their doesnt seem to be a hard and fast rule. One thing I do remember is that there is a free to enter national novel writing month on the net with the aim of producing 50000 words and if you do you get a certificate. Good Luck and keep us posted