Exasperated!!

Can someone tell me how to discipline a toddler?

Tara is so impossible sometimes. Whenever she did something really naughty, I would give her a stern look but she would continue doing what she was doing, while looking at me straight in the eye. Then I tried telling her 'no' with the stern look but she simply don't care and still carry on doing what she want. So I tried smacking her on her palm, from soft slap to a painful hard smack but she just refused to stop! She even offer me her palm when I told her I'm gonna smack her for being naughty, and go back to doing all the nonsense again. Exasperated, is the only word that can describe how I feel.

Are there any other methods to discipline her?

Gosh, it's so difficult being a parent.