As a copywriter, it’s hard to stop my ears steaming and my teeth grinding when I hear: “Great piece. Just one thing – you can’t start a sentence with and or but.”
That’s because it isn’t true.
There is no basis for the claim that you can’t start a sentence with a conjunction. It is just an age-old convention that’s as meaningful as warding of vampires with garlic.
If you want proof, then major dictionaries, journalism institutions and publishing houses all permit the use of conjunctions at the beginning of a sentence. And (see what I did there) more often than not and or but adds connection and flow to related sentences.
With this new knowledge fresh in you mind, know that the following sentence is grammatically correct:
And then she cried fowl. But in the end the grammar stickler didn’t get her way.
My suggestion is, stick this non-rule into the same musty old filing cabinet that contains your English teacher’s cane and throwing chalk. And please, leave your poor old copywriter be.