I have 18mos - 3 and half years in my house. Our house rules are posted and I tried to list them as what I want them to do instead what I don't want them to do. Trying to set a positive tone to the household. We have 4 rules which seem to cover things that come up in our house. I wrote them on a piece of paper with a picture next to each one. I'm not an artist but they know what they mean and can read them to you (even the 2 year old)
1. Be a good listener (pic of an ear)
2. Talk nicely (pic of lips)
3. Have friendly hands (pic of a hand)
4. Clean Up (pic of an arrow pointing up)
I repeat and explain these rules daily as opportunities arise. I try to praise often using the words from our rules. ex. If I say Please go sit at the table for snack and she does right away I say with a smile and enthusiasm "You are being such a good listener today. You went right to the table and sat down the first time I asked you" Hoping to make her want that reaction again even when it's more difficult. Start with recognizing small things and sound a little corny at first but it starts to come out more natural the more you do it. If she did not come to the table I would calmly guide her or pick her up and take her to the table after I asked her twice. I would calmly but sternly say "I asked you nicely to come to the table. I expect you to be a good listener." I try to ignore as much negative stuff as possible. I firmly state my expectations and stick to them. No child in this house is getting their drink if they demand "I want juice! or Get me juice!" I tell them "please talk nicely if you want something." I give time outs if their behavior hurts or was intended to hurt someone or something. Even little hits are not tolerated. I sternly say "I expect you to have friendly hands. Now sit down by yourself for a little while"
A good listener covers a lot of things. We talk about the tone of voice, common courtesy like please, thank you, excuse me, and volume of voice, and look on your face when we discuss talking nicely. Sometimes I make a game of changing my voice, tone, volume while we are playing and ask if that was following the rules or not. They usually laugh when I do that and it helps them understand what I mean by it. I explain when we are all happy. It's hard for a child to not only listen but understand new terms when upset. Friendly hands is about not hitting and snatching, breaking things. We talk about respect and personal space. Friendly hands also help others. Clean up means when you are done with a toy put it away and to clear your own dishes from the table, wipe up your own spills, wash your hands.
I repeat the rules often. I tell them how following the rules makes us all feel happier. I might point out when they are talking mean in a concerned voice "you face looks all red and your muscles are tight - that doesn't feel very good for your body" take a deep breath and blow out, change your face and put your arms down." I calmly talk them down. I tell them if they asked nicely their body would feel better and they are more likely to get what they want and I help them come up with a way to say it nicely if they can't think of it.