From Zinnser’s On Writing Well:

“Learn to alert the reader as soon as possible to any change in mood from the previous sentence. At least a dozen words will do this job for you: but, yet, however, nevertheless, still, instead, thus, therefore, meanwhile, now, later, today, subsequently, and several more. I can’t overstate how much easier it is for readers to process a sentence if you start with “but” when you’re shifting direction.”

YES! Tell them, Zinsser!

“Many of us were taught that no sentence should begin with “but.” If that’s what you’ve learned, unlearn it–there’s no stronger word at the start.”

You listening?

“It announces total contrast with what has gone before, and the reader is thereby primed for the change.”

I love it when really smart literary people agree with me. Fellow writers: There you have it from an authority on our craft. Use “but” more often.