Do you want a very simple technique for improving your writing?
Well, this is one that really works and you can start doing it from
today. Cut the length of your sentences!

It’s as simple as that. 

Long sentences should be seen as the enemy. They create confusion
for readers and they block clarity. And we all know how important
clarity is. If you have a long sentence in your first draft, take the
knife to it. Enjoy cutting. And don’t be surprised if you end up with
three or four sentences. Your readers will thank you for it.

Build a better vocab: http://grammar.ccc.commnet.edu/GRAMMAR/vocabulary.htm

Business writing training: http://www.actionwords.com.au/business-writing-course/