My son is 16 months old and has started to hit me and laugh mainly when he is being naughty or he doesn't agree with something he will hit me.. how can i stop this bad behavior before his brother is due in april?

I would put him in his cot for time out but i dont want him to think going to bed is a bad thing... but if he is being naughty and not listening i will tell him he can go to bed for a sleep and wake up in a nice mood (i try to this as little as possible)

Is there anything else i can try to do? I have tried smacks on the hand and telling him to stop but that just kinda contradicts things....