I incurred expenses in preparation for publishing and selling a book last. So is this something that I can take as a business expense against my taxable income?

Yes, you're allowed to claim business expenses without income, as long as you're working with the ultimate intent of making a profit.  Be aware that writing can be considered a hobby by the IRS unless there's significant promotion and professional activity to justify it as a business.

This is something with a significant promotional and professional activity. How do I account for this expense through Turbo Tax?

You can use "startup costs," which is most appropriate, though that will be limited to $5,000 with any remainder to be amortized over a period of years; other categories perhaps related to what you're indicating are advertising or "Other Miscellaneous Expenses," depending on what the expenses were.  I'm unable to edit hyperlinks in the "comment" section, but I'd suggest looking at these IRS publications for additional guidance:  <a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/i1040sc.pdf">https://www.irs.gov/pub/irs-pdf/i1040sc.pdf</a> and <a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/p535.pdf">https://www.irs.gov/pub/irs-pdf/p535.pdf</a>.

How do I do that in Turbo Tax?

If you'll type "start up costs" into the search box, it'll give you a prompt to jump to that area of the return.