What are some unique and effective ways to discipline a 1.5 year old?

From what Ive seen my mom friends do, be stern when they get too much out of control. You obviously cant be absolutely strict but a friend of mine imitates her baby throwing tantrums when she does. Like last week her baby bit my friends hand and my friend too bit her baby's hand (a little hard.) The baby got the msg and doesn't do it... This way I think so would work.