Mirror scrying is an ancient Celtic tool, but it's been used in all shamanic traditions at one time or another. The Celts just did more crazy things with it. Originally, its purpose was related to the military, as in looking into a pool of water to see an enemy's actions and/or shape shifting to a strategic location.
The purpose of shamanic practices lies in the duality of the path itself. The first necessity for those seeking a deeper understanding of the shamanic state of mind (or lack of it) is learning to access the peculiar areas of their own consciousness, allowing for heightened awareness beyond their cultural definitions of normalcy.
How do I do something more useful the next time lucid dreaming happens?
If you are really lucid dreaming, then you need to alter the fabric of the dream to one of your choosing.
What is the best use of stalking when doing healing work?
Generally, what I do is stalk a position for or with the client. Let's say I look at them and see X is their big problem, but going to X is going to create angst, or a negative reaction.
Life is but a player who struts and frets his hour upon the stage and then is heard no more. It is a tale, full of sound and fury, told by an idiot, signifying nothing.
All our lives we look at the world from a perspective of perceived immortality. To the shaman, there must be a clearer way of seeing the reality of this world and ordering the items we choose to place in our personal inventories. They have learned, over time, that the only way to develop a clear perspective is to take on the reality of their own deaths as an ally.