Will gladly trade service for a Pre-Order, Recommendation, Review, and Social Media Shares!

Don’t share more of your book than you need to. You want people to know exactly enough about it to be interested in your concept and characters, but if you show them too much, they’ll feel like they’ve already read the book and won’t feel a need to buy it. If your book has 13 chapters, I don’t recommend showing more than the first three, and not all at once. Rather than releasing one every week, release them as incentives for reaching certain pre-order goals:" Chapter 1 is up now, and if we hit 50 pre-orders, I’ll release Chapter 2!" That gives the incentive you’re looking for. You want people to feel like they have to earn more content from you; if you give it away, they won’t feel like it’s worth as much.
What you can do to help establish your brand and show off your storytelling without actually giving up book content is to release updates that talk about the world or characters of your story. Send out bios for each of your main characters, highlight interesting portions of the world of your story, etc. I had quite a bit of success with this.