A suggestion to imagine yourself going down stairs one step at a time and doubling your relaxation with each step down is one of the most frequently used visualizations in hypnosis scripts.  The metaphor "going down" represents the idea of going down into a deeper state of mind.  And then there is the direct suggestion that you'll double you're relaxation with each step downward.  This can be an effective way of deepening a trance state.

More hypnosis techniques:

Eye Catalepsy

Eye Fixation

Staircase Technique

Metaphors

Fractional Relaxation

Conversational Hypnosis

Indirect Suggestions

Double Bind

Guided Imagery

Visualization

Post-Hypnotic Suggestions

Direct Suggestions

Confusion Technique

Tongue Relaxation