From Daily vows and The Four Foundational Practices of Dream and Sleep

The third preparation involves reviewing the day before going to sleep, and strengthening the intention to practice during the night. As you prepare for sleep, allow the memories of the day to arise. Whatever comes to mind recognize as a dream. The memories most likely to arise are of those experiences strong enough to affect the coming dreams. During this review, attempt to experience the memories that arise as memories of dreams. Memory is actually very similar to dream. Again, this is not about automatic labeling, a ritual of repeating “It was a dream,” over and over. Try to truly comprehend the dream-like nature of your experience, the projections that sustain it, and feel the difference of relating to experience as a dream.

Then develop the strong determination to recognize the dreams of the night for what they are. Make the strongest intention possible to know directly and vividly, while dreaming, that you are dreaming. The intention is like an arrow that awareness can follow during the night, an arrow directed at lucidity in dream. The Tibetan phrase we use for generating intention translates as “sending a wish.” We should have that sense here, that we are making prayers and intentions and sending them to our teachers and to the buddhas and deities, promising to try to remain in awareness and asking for their help. There are other practices that can be done before falling asleep, but this one is available to all.

From The Tibetan Yogas of Dream and Sleep by Tenzin Wangyal Rinpoche