The only novel I found extremely difficult to write was one that I plotted chapter by chapter. When I write I like my characters to have the ability to surprise me. However, if they try to 'get out of hand' they do need to be put firmly in their place. I also like twists and turns in the plot to take me by surprise.
Before I begin writing I complete detailed character profiles for the main protagonists and name them. I have to visualise them walking, talking, going about their daily lives and understand their aspirations and fears etc.
When I begin a the novel I know what the middle and ending will be, the rest is an exciting journey for my characters and quite often for myself when I visit places of historical interest.