To follow up on what belleamie sugested if you are going to use the Casteneda technique, there is a gate to dreaming. I use it sometimes to put myself to sleep, although not for lucid dreaming.
There is a heaviness that crushes you when you are transported to dreaming. It has a weight to it as well, one that sometimes will jolt people awake with a feeling of falling. Begin memorizing that feeling and practice pulling it to you. I use it to force myself to sleep when I have a problem falling asleep and it is an excellent method to fall asleep.
Instead if using it to fall asleep, once you have mastered pulling it to you through willing the feeling to you, begin working on not losing your willed perception as you transition through that feeling.
I am very interested in hearing more about the heaviness. I think that is part of the hollow feeling I mentioned when I know I am lucid dreaming. Since early childhood while deep dreaming I have repeatedly had the feeling of falling, sometimes accompanied by an extremely vivid dream. Driving my car off an overpass or cliff is common. I fall, but wake up with a healthy dose of adrenaline right at the point of impact in the dream. I've become very curious about the tie between my physical sensations and the moment between waking and dreaming. I've assumed it has something to do with the chemicals released that keep you from moving while deep in dream space, and perhaps the counterpoint of adrenaline trying to get you to move.
I don't have a lot to share on this. I don't remember my dreams unless something startling is happening as I wake, and even then only if I repeat to myself or make a note immediately. If I don't do that it fogs up and disappears.
I have had a few lucid dreams, but there was always another party who went out of their way to bring it to my attention that we were in a dream.
You could be right on the chemicals, unless there is something taking place during all of this that is not tied to known laws we are imprisoned by. Like the horse tied to a chair who has been conditioned to believe the rope impedes its freedom and doesn't realize it can drag the chair wherever it wants.