To do the baby sign for careful, start with both hands in fist form, with your index and middle fingers extended at 90 degrees to your palms. This form is actually the 'K' sign in ASL. Take your dominant 'K' hand and tap it on top of your non-dominant 'K' hand to make the sign.
An alternative ASL sign for careful is to put one 'K' hand on top of the other 'K' hand, and together do a small, vertical circling motion towards your body.
We mainly use careful to warn our babies of impending danger and to teach them to handle things gently.
Use the careful flash card in conjunction with the hot and hurt flash cards. The idea behind incorporating this concept is to be able to warn your baby when danger is at hand. Use it when crossing the street, or eating food that could be too hot, or when handling something fragile.