It is better to be careful a hundred times than to be killed once. (often erroneously attributed to Mark Twain)
Look out for #1. Don’t step in #2 either.
When using an old saw, make sure the teeth ain’t broke first.
If I seem to give a damn, please tell me. I would hate to be giving the wrong impression.
We don’t care. We don’t have to. We’re the Phone Company.
If you have plans for tomorrow, be careful today.
If you can’t be good, be careful. If you can’t be careful, give me a call.
Careful as a naked man climbin’ a barbed wire fence.
Though honey is sweet, do not lick it off a briar.
Though care killed a cat, thou hast mettle enough in thee to kill care. (Much Ado About Nothing)