I think the idea is to be thoughtful of others the same way we would want them to be with us, to consider not necessarily what we would like in a given situation, but what someone with the particular background, history, temprament, etc of the "other" before us might like. I must be willing to resist imposing my goodwill. Perhaps the Golden Rule could be stated another way: "Do unto others as they would have done unto them."
An example of this in action might come from the traditional handshake. I was taught that firm is best, but it's uncomfortable to be at the receiving end of an over-squeeze. It's happened before to me, and more than once. I shake firmly, but my partner seems to be out to proove some point. Just so, if I shake firm with someone who has a dead fish hand, I overpower her. The thing to do is match the other: soggy for soggy, firm for firm. That's not the standard practice, but that's the nature of do unto others, seems to me. Real compassion and kindness requires a reading, a sensitivity, and a bit of creative imagination. It's not the thought that whoever I'm dealing with should appreciate what I'm doing because it's right or best, and what I would want, but rather to ask and consider the questions, what does he want? What does she want? What are the signals here, and how can I best be of service?
I pay attention to others today, and treat them the way they want to be treated. I do not thrust upon them my own ideas of what's best, but listen and look for signs that tell me what would be most helpful, most needed, and most appreciated.