How exactly do you meditate while practicing lucid dreaming?

Apparently meditation is great for improving LD success rate etc, but how exactly are you supposed to do it?
Do you just sit down and visualize things in your head or something?
What is the core definition of LD meditation?

Alan Wallace, in his excellent book “Dreaming Yourself Awake: Lucid Dreaming and Tibetan Dream Yoga for Insight and Transformation”, says the most appropriate technique is a shamatha (tranquility) technique called “settling the mind in the natural state.”

aac