"What was a misstep that you (or your publisher) made with publishing your first book--and how would you do things differently if you could?"
I've been asked to write a post about this. I sold my first book in 1986 while still in my 20s. Texas Wildflower was a genre historical romance sold to a publisher that was expert at publishing them so in general, it went well. My misstep was in contract negotiation. As in, I didn't. I lacked an agent and was too intimidated and frankly, grateful, to tinker with the boilerplate. The advance was low, but that's to be expected. The two issues I should have worked on were the royalty percentage rate and the terms of reversion. These hardly matter when you're in the first flush of your first book deal, but a book can have a long life if you manage to make something of yourself. You want the rights to revert to you so you can renegotiate with the publisher or sell to another. This was all new to me and now, 20+ years later, I'm still bound by that initial contract.
To the publisher's credit, they did raise the royalty rate, but they didn't have to. I'm just glad they did. My advice--get an agent. If you negotiate without one, at least join the Authors Guild. Key issues to look at--royalty rate, the meaning of "in print" and the terms of reversion. Also, the option clause. Good luck!
Causes Susan Wiggs Supports
Bainbridge Island Library, Field's End, West Sound Wildlife Shelter, Bainbridge Island Land Trust, The Authors Guild