"So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets."
This message has been ingrained in us since we were in kindergarten. "Keep your hands to yourself." and "Treat others the way you would want to be treated". It's the simplest of rules, but it never ceases to amaze me how bad we are at it.
One thing though, is that we often treat others how we would want to be treated as we are now. It is a completely flawed idea to think that what I want is completely what someone else would want to. You wouldn't buy your wife an Xbox if she hates video games but you happen to enjoy them. We, at any given moment, are entirely different people with different sets of needs. You cannot love someone the way you want to love them, but only the way they want to be loved.
What good news can you bring to a child whose dad is in jail and whose mother is feeding an addiction through prostitution? "You are a sinner and Jesus Christ died for you" is of little to no comfort. Be mindful of other people and you will communicate the gospel, whether by word or by deed. Jesus is a great communicator because he knows each of us intimately.
So in everything, do to others what you would have them do to you if you were in their shoes.