Can You Optimize Your Smashwords Coupons?

I'm approaching my first KDP Select giveaway (in May--stay tuned), but my conundrum is that the event will be for the second e-book of a series (Mirrors & Mist), and I'm worried about the appeal (or lack of) for a free e-book that's mid-trilogy. Obviously, if you don't have the first book (Crimson & Cream), getting the second book of a trilogy for free isn't that special, so I'm trying to make them both available for free over that short time period. I didn't go the KDP Select route with Crimson & Cream (Book I), so I'm trying to coordinate a preemptive strike using Smashwords coupons to coincide with the KDP Select event for Mirrors & Mist.

The problem is that while there are a plethora of websites to promote your KDP Select days on, I've found very few websites where you can promote your Smashwords coupons. If I happen to be missing any great sites to advertise your coupon codes, please clue me in! In lieu of that, I conducted a little experiment, which, unfortunately, fell rather flat.  Here's how it went:

After unsuccessfully scouring the Internet for sites that promote Smashwords coupon codes, I stumbled across some coupon-centric sites that allow you to post your free Smashwords coupon codes (along with all other types of coupons). I posted on several of these, using unique codes so I could track which sites were more successful in giving away free books. Unfortunately, I haven't given away any books on any of these sites in over a week since I started my experiment.

In case you're curious, these are the sites I tried giving away the free e-book coupon codes at:

Just because they haven't worked for me doesn't mean they won't work for you. And you aren't restricted to free giveaways, either. Smashwords lets you create coupons for percentage-off discounts as well. If you've had luck with this method, let me know if you have any good tips to share. Oh, and by the way, if you'd like a free copy of the YA epic fantasy adventure Crimson & Cream for yourself or to give away, here's a code you can use on Smashwords: HB78A.