Never intentionally hurt anyone.
I choose that over the "usual" Golden Rule of "do unto others" because while that is generally a fairly good rule, one problem can be the "as you would have them do unto you" part. I take very seriously the fact that what I would prefer and what someone else (always a separate being from me, needless to say) aren't necessarily the same thing. Sometimes I think the world is far too full of people who deem that others "would have done" according to what THEY (the deemers) would; and while, up to a point and in a lot of ways, that "usual" Golden Rule is a good one, there's too much room for people believing that their idea of what they'd "have done" must be the "gold standard" for everyone else would as well.
This is particularly problematic when the "deemer" is immature or needy, or has too narrow a perspective to know what SOME other people would "have done". Another problem is that egos come in all sizes, and what anyone "would have done" can depend on the size of his ego.
And, of course, since huge numbers of people remain incapable of extricating themselves from thinking according to stereotype (of one kind or another) that's one more way in which what someone "would have done to them" may be completely different from what someone else would.