In my opinion, avoid the Select program. I have defended "free" books on a regular basis but there are plenty of other ways to distribute your work for free if you choose to do so.
I jumped into the Select program and am counting down the days until I am back out of it. I have Nook readers waiting as well, and I'm not bashing Amazon or B&N. I'm simply saying that competition is a good thing and handing the exclusive rights to your work over to a single company is bad for everyone involved(other than the company).
My Kindle sales are actually very good, but readers that own a Nook, Kobo or other reading device matter to me just as much. Just my two cents.
Just my 2 cents, but I am a huge fan of the Select program. I tried Smashwords but sales were nothing there compared to Select.
Amazon and Kindle sales represent the VAST majority of the market. I have taken all of my books off of Smashwords and enrolled them in the Select program and have seen much better sales.
Obviously this will differ for everyone. If your an active marketer then maybe the Select rout isn't for you. But for my money, being able to throw a promo day up every three weeks or so gets a slow moving book back up on its feet with almost zero effort on my part.
I used a single day's promo to get one of my titles moving and this started shifting 3 - 4 copies per day.
I used the promo again on the last day of last month to give June a good start.
Since then.... Zero sales!
It appears that amazon have changed the weighting of free books to paid books in calculating their bet seller lists. When I first did the promo they were weighted equally, I think. This meant that you could establish yourself with a promo as you would fire up in the ranking.
Not so on my second attempt.
Now you need 15 free sales to count as 1 paid sale - so if you have a mediocre promo day then the end result will be that your best seller rank collapses. I've gone from being in the 30k mark to being 130k and my 3 - 4 daily sales have vanished.
Be warned. I won't be using this again until I can get clarification on it from amazon. If my experience is endured by others then they'll have to alter it again, as it's pointless tool for an author to give the product away only for sales to dive.
Depends if your book are fiction and part of a series. Publish book 2 and make people buy book 1 3 4 etc. But i do fact and travel guide nobody will buy my other book since it is one off deal. I would be better off NOT using Kindle Select.
I tried KDP Select on a few of my books. Never again. It totally killed my sales and I stopped doing it so I could get them back on Nook as well. I have more sales on Amazon, sure, but without being able to put them on PubIt (Nook) while in the Select program, sales took a huge nose dive. I wouldn't recommend Select to anyone, really.
I originally thought it would be a very good decision, which is why I gave it a try. I'm glad I tried it, because I learned, like others, that it was definitely NOT worth the loss in sales.