At around 18 months, children begin to grasp that there are certain accepted social graces. Start teaching in small doses, setting realistic goals. Greeting friends is a great place to start. Children would have been watching how you greet and interact with adults and children, and will be keen to learn.
1. Eye Contact
Good, solid eye contact shows others that we are both interested in what the person has to say and that we have confidence in our ability to listen. Remember to look someone in the eye when you greet them.
A friendly smile adds warmth and will make both children relax during the interaction.
3. Say "hello"
Introduce yourself if you have not already met "Hello, my name is ..." or if you know the person, you could say "hello, how are you?"
This is a Hello Song that you may want to use during group times to practise the new skills.
If you are wanting to find social stories about greeting friends or visuals, there are so many on Pinterest, or simply spend some time on google.