Making it unique and interesting will make it something people want, but doing that is not really the problem you will face. No matter what is inside your book, if you want to sell it you need to give them a reason to want it. It doesn't matter what you write while revising. That has nothing to do with marketing. Maybe the overall story is, but I assume you are not creating a whole new book.
The moment people will read your book, the moment they have it in their hands and start reading the words you are revising now, they have already bought your book. So there is nothing more you need to sell them.
The part where you do create this need, is in everything around that. Make the cover compelling. Use the space on the back to write a small piece about your book that will draw people in. And the best way to do this, is showing them something new. Something they haven't thought about. That will make them curious. And curious people buy a lot of things.
Also, you don't have to think of something completely new. You can also take some existing thing and use it in a new, different way. Or slightly adjust it. As a good example (not related to books):
While randomly browsing the internet, I found the most intriguing thing. Laser guided scissors. Laser guided scissors you said? What is that? Do I need it? Well, I can just draw a line right. Works as well. But lasers. It looks so amazing! The red line is so Majestic!
Needless to say I am now the proud owner of two pair of laserguided scissors. I bought them last year. One of them is still in the wrapping and the other I used only once. But hey, what do they care how much I use them? I still bought it anyway.
As an addition, based on the comments:
I'm not saying a book should not be good. Just that for trying to sell your first book, changing what's in it doesnt make a difference. Its better to write an amazing novel and worry about marketing later, than trying to do the marketing part within your novel. Marketing within a book is kinda useless, because the moment they read that 'marketing' they already bought the book.