1. Publisher or self-publish: The publishing world has changed dramatically in recent years and the Internet has made self-publishing considerably easier. If you self-publish you have full control of your book, but also bear all costs. A publisher is harder to secure and will have control over some decisions, but also absorbs many costs (e.g., printing, distribution, cover art) and also gains access to critical distribution channels, including identifying outlets to review your book.
2. Agent or no agent: With an agent you give a portion of your royalties to them. Literary agents work on a commission basis and are incented to find you the best deal so that their payout increases when you sell books. Though you give up some of your royalties, an agent is often your best chance to get your book proposal reviewed by a major publishing house.
3. Publicist or no publicist: Publicists bring access that is hard for many people to get on their own. They identify media outlets such as television shows, newspapers, and podcasts to bring valuable exposure to you and your book. The best publicists can cost tens of thousands of dollars and you will have to consider if their services are worth it to you.
4. What is the book's "hook": Every book needs a quick and compelling hook that captures attention. This is always needed to draw in potential readers/buyers, but also literary agents, publishers, and publicists if you go that route.
5. Who is the target audience: Don't try to pretend your book is for everyone - all books have a more targeted market. If you decide to use a publisher they will want to know exactly whom you are targeting and how big the audience is. They will also want to know how your book is different from similar books that have been written and if it has relevance to sell outside your home country. The target audience will also help you decide who to ask to "blurb" or endorse your book.
6. Write or ghost write: You would be surprised how many books are written by someone other than the stated author. Ghost writers are sought after and can make anyone come across as a gifted writer. Authors may not have time to write a book or find that a professional writer is better able to capture the voice they want to convey.
7. What is my platform: This one must be alive well before you publish your book. You must consider the best way to bring visibility to your book and contemplate platform options such as your standing as a well-known expert, your social media presence, professional speeches, access to different constituencies, etc.
8. What are my goals: Consider the reason you are writing a book to help hone your focus, especially because the outcomes are not always connected. You might want to make a lot of money but not care about getting great reviews. You way just want to build your brand by getting your name out there. You may want to achieve critical acclaim for your book even if it doesn't make a lot of money (think Indie films). Not everyone can be a NYT best selling author, but you can be pleased with the outcome if you know your goals in advance.
9. What format will the book be: You have many options. It can be hard cover, paperback, eBook, audio, small, large, etc. If you self-publish consider the costs of developing multiple formats, particularly hard cover and paperback.
10. How much time will you commit: The reality is that a book once published is there forever. In addition to the time it takes to write (or work with a ghost writer) you will also need to spend time promoting the book. You must consider you ability and willingness to travel, speak, go to book signings, and otherwise invest your time to market and sell your book.
No series of decisions is right for everyone and you must consider your particular situation and goals. One last tip: don't get too fixated on the title of your book - it often changes as the writing process progresses, especially when you have a publisher and and editor.