The best advice my mother ever gave me was two sentences.
Do more good than harm. Spread more joy than sorrow.
I'm still amazed how many times I use that as my solution to ethical questions. It's all fuzzy thanks to what you'd call "good" and what you'd call "joy" but - it works for me. The "good" doesn't mean you work for hours to make everyone happy. It may just be something simple like cleaning your kitchen floor and then enjoying a cup of tea and a chapter of a book. It's joy and good work.
Two sentences. I think that's why I love poetry so much. A book gives you room to spread out the words and be verbose and thematic. Poetry is all condensed like crystal and shimmery at the edges. Edges that can be sharp or just percise. A book for me is a lot more - like a wide expanse I can play in. I think that's why I get growly at badly done 'clever' books. I want a story, not to see the author polishing his/her pride.
And now, I rest.