Sam Harris wrote a whole book on this called Lying if you're interested

"You’re looking very ugly today." *A war starts!

I think lying is an important thing as long as it doesn’t hurt anyone.

Religions and god-beliefs would be far less prevalent.

I highly recommend everyone watch the movie, "The Invention of Lying" if you have not seen it.

Some things would be avoided, but many others would be highly destructive. Diplomacy is often the art of telling a lie in a polite and seductive way to avoid conflicts.

Make sure you don't lie and assume nobody else is lying.

Then act accordingly.