Help them when they need to be helped.

cheers him up.

smile at their faces. speak with them in a nice way. doing some works for them as they hard to them to do. help them . trust on them. always stand beside them.

Treat them the way you want to be treated.

First I want to ask you this question why you asked this question? If you think that by doing a lot of things to make others happy and finally you will be happy I guarantee that you will not be happy because all of us experienced a bad feels caused by others whom forgot what we do for them. I think that is better for you to built your happiness from in side of you and build your own world where you can live your life , and don't spend your life looking for happiness that others may grant it for you, but this dose not mean to a polite man and do a lot of things for others but you must separate your happiness from their happiness.