My 10-year-old son brought home a book from our park’s free library box. It was a biology textbook – teachers edition. He said it looked interesting and hey, it was free (having no idea you could sell it). I scanned it in my Amazon seller app and realized it was worth around $150. He was so excited. We listed it for sale for $130 and it sold! Going to tell him, he just made $130!
Education occurs most often in "real life" by becoming involved and learning the details as time progresses. Although there are several books on the topic, some so-called "how-to" or "silver bullet" books instruct readers to manipulate holes in the Google algorithm, which can quickly become out of date, or suggest strategies no longer endorsed or permitted by advertisers.
If you have pop-ups and optins on every page, I would have to think that it would be a lot harder to convince someone to link to it. Especially since the pages where you have your optins (and probably receive the most traffic) are probably the same pages that you have your best content on as well that you'd be hoping to pitch in your outreach campaign.