S.T.
My daughter is 20 months old and recently went through a stage where she would hit me if she didn't get her way. I tried slapping her hand only once and stopped when it only made her get more aggressive. I found for her that the most effective punishment is to put her in the corner. I stand right behind her so that she can't get out and I count out loud. I start at 15 seconds and for every repeat offense I add five seconds. She sits there like she doesn't care that I'm doing it, but usually after the first time in the corner she stops. I've only ever had to count up to 25 for her. I've heard of the rule of thumb of a minute for every year of age, but deemed one minute too long for my toddler. 15 seconds seems to do the trick. The bonus is the counting out loud gives me a chance to cool down if she's managed to rile me up over whatever she is done.