I just posted this same question the other day. I am reposting one of the great answers that I got from Rebecca M. Hope this helps you.
Alot of the other moms also told me that I shouldn't hit cause this will cause your child to hit also. Also do not yell. Try to be calm and to also ignore them when they do these things. They are just trying to get a reaction from you. If you ignore them then they will stop. Just go about your business and don't talk or react to them. If you would like check out my post and see the answers that I received. My post is trouble with 2.5 year old. Good Luck!
Here is Rebecca M's response to me:
In my 16 years working with kids I've never found time outs to help. They just cause more fights. Here is what I've done in the past & it WORKS! on all the kids I've worked with over the years.
1) Never go to the store before a nap or meal, that sets children up for failure.
2) Tell your child what you're doing before entering the store, it helps them anticipate the trip.
3) Tell your child how you want them to behave, it sounds simple but often kids honestly don't know.
4) Give choices, toddlers need to feel in control. When they do not feel in control, they act out.
5) Be consistent with consequences. The kids in my care knew if they did not obey there would be consequences EVERY time, do they ALWAY obeyed.
6) Praise for good behavior. Toddlers what to please more than anything, so the more praise you give the more you'll see that behavior.
If you do this everytime, you will see a change. I keep stickers in my purse to give out when I say good behavior, you could play a game, if she gets 5 stickers, she can ___________. Go to the park, choose a toy or snack what ever.
Good Luck,