I definitely favour using an outline. Starting with a ‘nugget’ of an idea, expanding that by setting milestones along the way for your story, getting your ‘climax’ and ending/resolution clear early on, working on your opening scene and major turning points – and of course knowing your characters well – all helps for slicker writing.. The ‘outline’ doesn’t have to be a chronology at the start, sure you must get down to writing the novel ‘scene by scene’ eventually but having the big picture clear from the outset helps. I think this approach does leave you room to deviate, to explore fresh turns as you travel the journey with your characters. On a more techie point, the document map feature in Word is a useful tool – you can collapse or expand your scenes to move from overview to detail – and shift chunks of text/scenes around.