When signing to your baby it’s important to use the appropriate facial expression along with your signs. Naturally, not all signs require a facial expression, however when they do apply, they should be congruent. This will help your baby associate the sign with the emotion the word is meant to reflect.
Some words where you might use facial expressions include emotions such as HAPPY, SAD, ANGRY, SCARED/FEAR, and FRUSTRATED, as well as sensations such as COLD and HOT amongst others. Remember that sign language is a visual medium and it is meant to make up for the loss of hearing. So when you sign feelings and sensations make your face light up with the associated facial expression. HAPPY means a smiling face, ANGRY means a scrunched up face with furrowed brows and so forth. When you first start signing use as much expression as you can muster. It’s far better to use too much facial expression rather than too little.