To sign important, form the ASL letter F sign with both hands, then touch both hands at the tips where the index fingers and thumbs meet. Then separate them as you move each 'F' hand downward, then swoop each up again until they meet at the top and center in front of your upper torso.
Imagine forming the shape of a pretzel or two angel wings touching.
Teach your baby or toddler the important sign when you are explaining that some daily routine is necessary and important to do, whether they feel like doing it or not. Things like washing hands, bathing, dressing up, and eating properly are fundamental, good habits for your baby or toddler to develop early on, so this is an important sign -- pardon the pun -- to teach them!
This is a useful flash card taught best in conjunction with the flash cards of important habits, routines, and concepts that your toddler should learn early on.