It's important to know the exact result you want before you begin. Then make that result happen by ending your message with a specific call to action (or CTA). A call to action might be "call us now," "use this discount code in our shop," or "schedule a demo." Make sure the CTA is direct and appealing, and that you show the reader why it's worth their time to click, visit, or call.
The books I've written have actually had three different titles, updated to move with the times. My first text book was titled: Internet Marketing: Strategy, Implementation and Practice. I then created E-business E-commerce Management and, with PR Smith, E-marketing Excellence, for professionals a couple of years later. Then, much later, the names switched and in 2012 we renamed the Internet Marketing book to Digital Marketing with the others becoming Digital Business and Digital Marketing Excellence. About time too, since I was involved in developing the syllabus as an examiner for the first IDM Diploma in Digital Marketing back in 2004-5 when the term was hardly used at all - so it's been great to see 'Digital Marketing' adopted as the 'de facto' term, when I was first involved in defining it with the IDM students in 2004!
Testimonials – If you work with contractors or freelancers, you can reach out to them to offer your testimonials in exchange for a link. Moreover, if you are using consultants’ or specialists’ services, you can also do the same as you do with contractors. Lastly, if there are customers who are happy with your product or service offering and they do not mind you linking to their site, this could be a good opportunity for your business.