on Jane Friedman site:
When doing giveaways as an author, it’s important to conduct a lawful giveaway (and stay on the right side of Amazon’s terms of service) that protects the rights of the entrants.
Before I outline important principles to follow, I’d like to recommend Rafflecopter, a free-to-join website that makes setting up a giveaway easy. In fact, a number of the techniques I’ll discuss are specific to their platform. Rafflecopter takes a lot of the work off your shoulders. You don’t have to worry about storing entrants’ information and keeping it private, because this data is stored by Rafflecopter. You also don’t have to manually input entrants into a random generator to pick a winner; when you’re ready, Rafflecopter will do that for you at the click of a button.
Through Rafflecopter, you can create a giveaway form for your website. People who want to enter can easily do so and earn points by completing tasks such as visiting a Facebook fan page or tweeting a message about the giveaway. (More on that in a bit.) Rafflecopter also provides a direct link to your giveaway page, which you can use when you announce the giveaway on social media sites.