"You may not learn much from this book but you won't be bored I occasionally buy 99c books but this is the first one I ever read all the way through, going to read the next one right now" - that's the latest review - the 99th review on the first book in a series selling at .99 cents.
I started writing seriously in 2009. Put out my first novel in December 2010, and one a year since. Between the Day Job, and how much I think about the story before I start writing, one a year is my goal. Between the three novels I sell somewhere between 250 and 350 a month, the vast proportion of that between the two books in the series - a third is being added this year. As I mentioned above book #1 sells for .99 cents and Book #2 sells for 4.99.
I've been fortunate to gain a group of followers who seem to like my work, and within that group some hard-core junkies who're on me for a new release all year long - I love them dearly, I do, they're the carrot and the stick all rolled up in one.
A couple of things I've noticed with the series books:
1. Book #1 always starts out strong out of the gate, the BBOS are usually gone by mid-day, and leads the sales through the month; until the fourth week when Book #2 surpasses it. From anecdotal evidence I reckon this is people who've read book #1 going on to buy book #2.
2. "Bad" reviews don't affect sales - not one bit - of course it helps if you have a bunch of good ones to offset and it's scary when you first get one. After the third or tenth, you just think "oh well," and move on...
3. Book #2 has about 10% of the reviews of Book #1; reviews will come, just be patient. The reviews of Book #2 are higher than Book #1 (the people who didn't like your style have left).
I don't do much marketing, occasionally buy an ad; I've never tweeted "buy my book". I have a website where every now and then I pontificate and a FB page where I keep in touch with my readers. I do my own covers (each costs about 10 dollars and a day's worth of time, and ebook formatting. I have an awesome editor, who's lovely, diligent and patient.
I'm not on any top 100 lists although I've been there a few times; both free and paid. I'm not in Select anymore but it was fun while it lasted. I sell about 5% print books to ebooks. 97% of all sales come from Amazon.
Every month for the past 18 months sales are higher than the month before. It's just the beginning.