It's common to hear people refer to the "terrible twos," but many of the parents in our social circle (including my husband and I) struggled more with behavior issues when our children were age 3. I wish I had known about Education.com back then! Below are some links to info centers that include discipline strategies you might explore with your son. I hope this helps. Thanks for asking!
I've learned that with kids you need to establish that YOU are the boss. Put your foot down when he starts to disrespect you. Do not give him what he wants when he behaves that way because it will make him think that he is being "rewarded" when you finally give into whatever it is. I know that it's hard to discipline a 3 year old, but you must be stern when it comes to disruptive behavior. Nip it in the bud.