Gentle

Make your non-dominant hand into a fist, then gently stroke it with your dominant hand (i.e., the ASL sign for slow). The sign is as if you were gently stroking a little creature, so when you do the sign, the motion should be slow and your body language relaxed.

A popular ASL sign for gentle is actually both flat, open hands, palms facing down. Then make both hands gently do a sideways, patting motion, as if you're patting the heads of small children in front of you.