You should necessarily read this. It’s a great tutorial which helps to understand why so many lucid dreams write in their books or just say that DJ and DR are the most important things in lucid dreaming. When you train your dreams’ memory your brain automatically inserts more awareness to the dream realm, because when you are more aware of things around you it is easier to remeber them. And when you are more aware in your dreams without any reason you start noticing dream signs or just out of nothing become lucid.