I think the very simple think we can all do to make this world a nice place is "SHARE". The basic act of sharing from every individual can make a society progressive, peaceful, economically strong, morally strong and above all harmonious.
Here's what I mean by sharing: Every individual shares what he's got with his fellow human beings and in return they do the same. A person with some kind of skills can share his skills so that more people can benefit from them, a man with money can share some of his wealth with the most unprivileged ones, a leader shares his insights, a wise man shares his wisdom, a scholar shares his knowledge, a kind man shares his kindness, an innovative man shares his ideas and so on. The colective effect of all this sharing can make this world a nice place, that's what I think.

Hope my opinion helps you. Thanks.