Don't think about pink elephants!
Of course you already are, aren't you?!
In order to make sense of what I said, you have to conjure up a pink elephant so you know exactly what it is that you aren't supposed to do in order to make sense of the instruction.
That's exactly what happens when you tell a child:
"Don't argue with me".
"Don't answer back".
"Don't drop the glass".
Instead, tell your child what you do want them to do. It's much easier for a child to process a positive statement and to understand what he's to do when told specifically.
I had a client the other week who was so tired. She told me that every night she told her child "Don't come into my room" but every night she did. I suggested that 'if you always do what you've always done, you'll always get what you've always got'. She realised she needed to make a change in order to get a different result. But what can I do, she asked?
I said "well what do you want her to do?"
"I want her to stay in her room" she said, almost surprised at how different that sounded. She hadn't even verbalised to herself what she wanted to happen.
She emailed me the very next day and said it had worked.
I find it remarkable that she hadn't thought of that but when you're tired and frustrated it can be quite easy to just keep repeating the same things. You just hope that eventually what you want will happen. It won't. It's you who has to change.
Think about what you do want, or what you want more of and make it clear to your child. Demonstrate it - be the change you want to see. It's no good telling them not to do something they hear or see you doing all the time. They need you to be the model of what you're asking of them.
So focus on what you do want and you'll start to see some positive change.