It's hard to say what the best advice was, but I know for sure it came from my dad. He always gave great advice.
But the one that comes off at the top of my head is something that he said to our dog. I was eight/nine at the time and we were walking our dog, Shadow. He was barking at a squirrel in a tree (he hated those things, because one used to taunt him), so my dad told Shadow to be nice to creatures both big and small. The conversion was lengthened, but the lesson learned (one that he taught me since I was just learning to walk) was to always show compassion and kindness to those around us, be them human or animal.

He was amazing like that... I miss him so much.

Worst advice is more hard to remember, because I never listened to it. The only one that comes to mind is a family member (outside the house) suggesting that I get rid of my animals to make things easier. Which would never happen, my animals are my family (more so than the said person). Because real family doesn't turn their back when times get hard.

I'm sure others have given me other bad advice. But I don't remember them right now.