Short Answer: Don't

Long Answer: There are lots of places where you can make a lot more money, with much fewer hassles

We work in lots of markets and Authors and Publishers are not a good market to work in

If you can avoid this market, avoid it

There are a few reasons why Books and Publishing is not a good area to expand into

1) The Large companies in this ecosystem as extremely predatory and out to kill everyone. They are against anyone at all making money in the ecosystem
If you find a profitable business they start feeling a deep sharp pain in their appendix

2) There is absolutely no filter any more so everyone and their mother is an author now
It suits certain people in the ecosystem to create this deluge of authors. To have each new author believe they have a chance at success and riches. So there is no one reminding these authors that they actually need to create a good product

3) A significant percentage of authors have been burnt in the past and are now suspicious of everyone

4) No one knows where the ecosystem is going to end up. You might invest in something that is completely non-relevant by the time everything shakes out

5) There are massive manipulations in the ecosystem. Things that are so illegal even Venezuelans are aghast
Sites get 'disappeared' from the Search Engines
Books get 'disappeared' from the Bestseller Lists
Authors get 'disappeared' from the Book Stores

6) The large companies and the large Publishers are scared to death of the coming changes
At some level they know they are going to get Dinosaur'ed
They treat everyone else in the ecosystem as Dangerous Mammals
You come in and start doing well, and suddenly you are perhaps the Mammal that will take over from the Dinosaurs

7) An Intelligent Enemy is better than a Stupid Friend. This ecosystem has
Stupid people who control the ecosystem (or at least try to)
Stupid Enemies
Stupid Friends
Unless you're John Rambo you really don't want to get stuck in here

8) There is a lot of jealousy of any one who becomes profitable and successful

The ebook stores made billions of dollars of investment into ereaders and ebooks
Sony gave up. Barnes and Noble is struggling. Amazon is stubbornly continuing to make ereaders

Everyone had the dream of selling $9.99 ebooks which cost 1 cent to 'digitally print and distribute' - generating profits of $3 to $6 per ebook for the stores
Instead, $0 ebooks and $0.99 ebooks are beginning to wipe out $9.99, and in the future might wipe out $4.99 and $2.99 too
Bye bye $3 to $6 profits per ebook. Hello 15 cents profits per ebook

The large companies are still in La La Land thinking they can brainwash readers into $9.99 purchases. Reality is telling them they won't be making any money from selling ebooks

Now you stroll in and find a profitable business niche (of which there are many). The large companies feel an incredible sharp pain in their appendix. Then a throbbing headache in their tiny dinosaur brain. As they realize that after 10 to 15 years of investment, after billions and billions of dollars of investment, they will be left trying to make money from $0 ebooks and $0.99 ebooks

While you will be making money hand over first

They are not the type to let you make dollars while they make pennies

9) There are basically monopolies
Monopoly on the book store side
Monopoly on the advertising of books side

So you would have to figure out some way to work around these multiple monopolies

10) The large companies and the monopolies seem to have hidden silent partnerships
Making it even tougher for new companies to protect any profitable business niche they find

Really, it's not a market you want to get into unless you're Chuck Norris or John Rambo. Lots and lots of markets that are much easier to work in