One prevalent myth is that we are thoroughly civilised. Bur really we are quite barbaric. The multi-millennial process of putting brutality and ignorance behind us is but half completed. We will be known as unsophisticated and narrow minded in the future.
Disabusing oneself of myth leads to mild nihilism until the novel void is appropriately filled. What is the rational, civilised cure to the horrible realisation that I am a hot-headed brute, an ignorant Scythian?
Take a long-term view of Science.
The current theories will be supplanted by others. Some studies will be contradicted. Some will be confirmed. Science may be our best methodology for knowledge acquisition so far, but it is still in its infancy. Statistical studies are highly fragile. Maybe that's because statistics is just over a hundred years old.
Respect the past, including elders and tradition.
Some things progress (like technology), but other things are relatively static (like the structure of human brains). Some ideas survive because they really are robust. What do you do when grandma contradicts Science? It's not always safe to go with Science. Some domains are more suited to ancient wisdom than to the latest intellectual craze.
Be suspicious of static governance but allergic to revolution.
All the violent revolutionaries were wrong for their violence, but right that governments need change. Changes to governments need to flow gradually out of an abundance of courtesy. The United States constitution, for example, desperately needs modification. But the process of modification must be civil, unlike the war that produced that constitution in the first place.
Defend against major and catastrophic regressions.
I said that civilization was half done, but the story could blast to a nuclear end tomorrow. Progress is not inevitable and will not be monotonic. My thesis errs optimistically, but intentionally, to inspire the hope requisite for action. We must defend society against regressions and maintain existing good systems all while we try to improve. Unfortunately, novelty frequently exposes us to new risks. So defend, maintain and innovate.
Find ways to treat people better.
Both personally and systemically throughout society. Innumerable smart, 'nice' people were party to slavery, misogyny and oppression in the past. Few could see past the social constructs of their time and fewer had the power to make those changes. More change is coming, so grab every loose thread of society's straitjackets and pull until the unfortunate win.