In the future, I might try an experiment (for us at Daring Entertainment, anyway) with a KICKSTARTER.
First of all, I hate doing Kickstarters, but they've become a necessity in the industry nowadays just to generate hype for a book. Honestly, all I want to do is write the planned book, produce it, and publish it. I don't want to feel forced to schedule extra books or materials right from the jump just to get funded.
Kickstarter is honestly one of the main things that has turned me off working in the industry.
So what I might do moving forward . . .
Kickstarter the ONE book I'm looking to do, only. Three tiers, only: PDF, softcover, KS exclusive hardcover. The Kickstarter edition of the book includes an extra chapter that will never be released in retail.
MAYBE an accompanying 32-page adventure that is provided free to all Backers. Depending on the Kickstarter, the adventure might go retail at a later date, or it might not. But Kickstarter Backers get it free just for backing one of the three tiers.
In other words, I might start treating it as a single book pre-order format, with the exclusive KS chapter, exclusive hardcover edition, and a freebie to all backers.
Which also means I can run the Kickstarter with a lower funding goal, as well.