The single most important thing is to read to them. Every day.
Yeah that! I didn't do anything other than read to my DD1 and help her develop a love of books and story telling. Actually the only other thing was to get her to draw her story in pictures, then tell it to me and I would write it for her. She is reading and writing at a level almost 2 years above her age currently and loves books. The Mem Fox book is great but basically reinforces the "read, read and read some more" approach.