The simple way to get better at business writing

Don't do business writing.

Have you ever met someone in industry who talks like he writes? You visit a store and the person says, "effective January 1, 2015, we have ceased operations at this location. For further information, correspondence should be addressed to our headquarters." Of course not. That would be awkward.

Write like you talk instead.

"We closed this store last year. Sorry for the hassle, please call us if you have any questions."

With effort and practice, it's possible to speak with respect, precision and energy. After you speak that way, write down what you said. 

That's effective business writing.