2. Avoid offering freebies on Amazon: you may trigger a “scam” algorithm
Be aware that your free titles may be affecting your rankings, as Amazon strives to eliminate fraud. If you read the KBoards thread linked above, you’ll see anecdotes of free ebooks harming an author’s sales.
In September, Amazon started to clean house to eliminate scammers, unfortunately this algorithm change seems to have impacted innocent authors too.
Free ebooks on the ebook retailers are much less useful than they were even a year ago. Until the dust settles, you may want to avoid offering permanently free ebooks.