Question

What is "proper" about using "But" or "And" to start a sentence? Anything wrong with it?

Answer 1

Do not quote me, I am no expert. I would google exactly what you have asked and see what pops up. In my experience when using 'but' it follows a comma. For example, "She said she had to wash her hair, but she was probably lying to me." As for starting a sentence with 'And', I would carefully investigate it's usage somewhere reliable like Purdue's OWL website.

Answer 2

That's a great start! Thanks!