Your hands, used correctly. Applying products with gentle, upward motions and using your ring finger for the delicate eye area prevents tugging and pulling that can contribute to skin stretching over time.
Sleeping on your side or stomach can cause creases and "sleep lines" on the neck. Try to sleep on your back, and use a silk or satin pillowcase to reduce friction.
Use gentle, upward sweeping motions when applying serums and moisturizers. This technique helps support the skin's natural contour and avoids dragging it downward.
Use a balanced moisturizer with humectants (e.g., hyaluronic acid) and barrier-supporting ingredients (e.g., ceramides) to maintain hydration and resilience.