For SaTaNaMa, the S is hissed, the T is more like THZ in pronounciation, where you place your tongue behind your front teeth and try to make a TH sound while maintaining the tongue position.
The mudra associated with SaTaNaMa is: Vibrate Sa with thumb and pointer finger together at the tips, then Ta with thumb and middle finger, then Na with thumb and ring finger, then Ma with thumb and pinkie finger together. This is not completely necessary, but might help increase the effects of it.