I've found that the most effective method has been a consequence with a countdown.
eg Yasin you have 5 seconds to stop smearing yogurt on the TV or I will put one of your trains away and you can't have it back until next week. 5, 4 3, 2, 1 ok Yasin. I asked to to stop smearing the yogurt so now I'm taking this train away. Screaming and shouting and tears from Yasin. I'm sorry you're upset Yasin but I have to take the train away because you didn't do what I asked you to. Yogurt is meant for eating not painting.

I try and make it fit the circumstances so if he's bashing the cat or Imran with a toy I remove the toy that he's using to bash the cat/his brother.

I've always followed through on it and these days both the boys know that once I start the countdown that they're better off doing as they have been asked.