Here's an exercise that we did once when I was taking a class on translation, and I thought it really helped in being mindful of voice and how to switch it to convey different information.  The idea is quite simple. You can do this exercise if you're working on a big project, like a major paper or a book.  For the class, we had an extensive 20 page paper due by the end of class on a topic that we had been steadily researching.  


Picture that you're in the following situations.  Then, try and explain your novel/idea to the person in these settings.  Try to sell them on your idea and communicate.


1. Meeting an elderly woman on the bus.  By chance you and she strike up a conversation after she drops something, or someone bumps into you.  You tell her you're an author, and she asks you what your book is about.


2. You and your best friend are chilling at a bar.  The music is going, people are all around, and you and he/her have a moment where you can really talk.  "So, what's this novel you're working on?" he/she asks.


3. You're in a board meeting with some imposing looking executives in full business attire.  You've just shook hands with each one, and you're thankful that your connections with the secretary got you this meeting at all.  They're interested in your idea/novel.  How do you sell it to them?


This not only helps with say, book descriptions for product listings or teasers for your work, it's also a great way to stop and ask yourself: "What's my voice?"  What tone do you take when you write and how would switching it up change your style?