Four out of every five folks say they have at least one book inside them -- and, as an entrepreneur, you’d better be one of them. Publishing a book is a savvy business move because there’s no quicker or surer way to set yourself up as an authority in your field. Especially considering that of the 85 percent of American businesspeople claiming they want to write a book, only 5 percent actually do.

That's unfortunate, because surely they know that there’s nothing better for instant social proof of their clout, credibility and competence. Imagine citing examples from your own book or being introduced as an author at an event or on a podcast. The credential raises the bar to a whole new level.

But publishing your book is just the start. Once that event happens, the real work begins for turning your book into a revenue-generating asset.

Related: The World’s Best Marketing Tool: Writing a Book

So much to gain from giveaways

Some of the most successful entrepreneurs have capitalized on the giveaway approach, including Danny Iny, founder of Mirasee, a marketing and education firm. According to Iny, readers who have downloaded his free ebooks have often subsequently converted: They've bought print copies for colleagues or retained his firm for its flagship products and services, increasing Iny's overall sales.

So, yes, absolutely, a book will get your business message out there. And giving it away will get it into more hands. That move is great PR for both your status as an author and your business. You can’t beat it in terms of cementing your expert status.

Most importantly, though, writing a book has to have an underlying business objective. For me, that objective was sending qualified leads to a proven sales funnel.

From $0 to $4 million in sales

In February 2016, my business, LinkedSelling, launched a coaching program called The Appointment Generator. To kick off the launch, I wrote Booked and self-published it on Amazon. We ran promotions throughout January to get people to pre-register for the book. Then, in the first week of February, we gave the book away for free.

Tens of thousands of people “purchased” the book for $0, in exchange for signing up for our email list. Each person then went through a well-tested sales funnel, which expanded on the ideas in the book through a series of videos and webinars. The culmination was an offer for the program, which in turn generated $4 million of sales.

Booked was a crucial part of this funnel -- it proved to these prospects that I knew what I was talking about by laying out case studies and demonstrating that my company is good to work with.

The book isn’t the first or last step.

Too many people write a book and think that’s that. But, they're mistaken: The big-time results come from working a two-pronged plan: Your proven back-end sales funnel is already in place, and you’re marketing effectively. Here’s what you need to do:

1. Focus on the funnel.

If there isn’t a next step after giving the book away, you can’t nurture prospects and turn them into clients. Once the sales funnel is in place, test it with cold traffic for four to six months before the book launch. For example, with Booked, we drove about 2,000 opt-ins to a PDF ebook version from Facebook ads.

That let us test the offer extensively to see what worked and what didn’t -- before prime time. Then, in February, we had things dialed in and generated about 90,000 leads.

2. Make an offer no prospect can refuse.

Authors don’t receive any information from Amazon about who buys their books. To get your prospects’ emails, set up a landing page where they can submit contact information to be notified when the book goes live or when the free period begins.

Incentivize this participation with bonus offers such as “Give us your name and email, and you’ll not only get the book for free, but you’ll also receive a complimentary video training series and companion workbooks.” Without that extra incentive, they’ll just go get it at Amazon, bypassing your opt-in and sales funnel entirely.

Related: Why You Need a Stellar Landing Page to Convert Prospects

3. Don’t fade away.

Once you’ve captured qualified leads, don’t let them go cold. Nurture those warm leads with relevant content, email campaigns, videos, webinars, etc. Stay in touch with your readers; you’ll continue to build important relationships even as you educate your prospective and returning clients.

4. Be your own megaphone.

Promote your book in your email signature and social profiles. Even my LinkedIn headline has a call to action for a free copy of Booked. Keep copies in your car trunk to give away at networking events and for when you meet prospective clients in person. When you’re a guest speaker or keynote, ask the host to introduce you with your book title.

When you hear breaking news relevant to your subject matter, reach out to local reporters as a resource. You can even sign up as a source with Help a Reporter Out so journalists working in your area can call on you for expertise. Each interview you give generates a plug for your book.

Serial entrepreneur David Niu, founder of TINYpulse, had another winning move with his book Careercation. After visiting with prospective clients and identifying their pain points and other particulars, Niu made a practice of highlighting pertinent and helpful excerpts in his book before sending it over to the prospect.

Being a published author in your niche is a big deal. It brings prestige and other intangibles that affect your reputation and brand, resulting in stronger word of mouth and warmer introductions.

Make your book into an even bigger deal by giving it away. This strategic generosity can send thousands of new prospects your way. With the right approach, you can turn those prospects into repeat customers, and your book can turn into a major source of growth.

Related: 3 Not-So-Obvious Steps to Writing a Successful Business Book