I have found some people quoting this as Vonnegut: "Never take liquor into the bedroom. Don’t stick anything in your ears. Be anything but an architect. Live in a nice country rather than a powerful one. Power makes everybody crazy. Get somebody to teach you to play a musical instrument." But as Einstein said, "Be skeptical about things you read on the internet."
I have also found the following passage published in Letters by Kurt Vonnegut, in a letter to Sam Lawrence:
"Advice my father gave me: Never take liquor into the bedroom. Don’t
stick anything in your ears. Be anything but an architect. Your good
mother is putting a present in the mail for you. Cheers, K"
And in another letter to Nanny Vonnegut:
"I think it’s important to live in a nice country rather than a
powerful one. Power makes everybody crazy."
And yet another letter to Nanny:
"Also: get somebody to teach you to play a musical instrument"
So, it appears that your skepticism about The Guardian was misguided here, the online quotes are an agglutination of loose bits, though, and half invented, since a part of it is about advice he got from his father.