You're not going to know everything involved in this process right off the bat (in fact, I still don't), so don't be afraid to ask for help! Having someone who has done this before to advise you and help you along makes things go a lot smoother.
Tip 2: Ignore your book
Ignoring your book for at least two weeks allows you to look at it with fresh eyes so you can catch more errors and be more critical of your work (and therefore create an even better end product).
Tip 3: Be critical
While we would all love to just instantly think our work is perfect, we can't afford to do that. Being critical of your work is hard, but it's necessary to publish the best version of your book.
Tip 4: Do your research!
Know what you're getting into (preferably before getting into it). The process will go much smoother when you know what you need to do and expect.
Tip 5: Learn from others!
There will always be people who know more than you and/or have more experience in certain areas. Take advantage of that! Constantly being open to learning is key to constantly improving!
Tip 6: Make a plan
Know what you're doing and when you're doing it. Having a schedule or plan keeps you on track (and makes this whole business of promoting a book yourself WAY simpler).
Tip 7: Be consistent and creative
This isn't something where you can get away with just disappearing for a while (take it from someone who tried that). Improvement and visibility for your writing only comes from consistently showing up. But while you do that, make sure you're showing up as you! Your uniqueness is what makes what you bring to the table so special.
Tip 8: Keep your passion in mind!
Remember why you're doing this in the first case! There's a whole lot to keep in mind with this entire process, but the most important thing to focus on is why you're doing it. If you lose your passion, this is going to get a whole lot less enjoyable.