For example, the content on Super Weddings is useful whether you're organizing a wedding today or next year. All the content on the site is created accordingly. To make things easier for the audience, it is separated into categories to make it very convenient for the reader to find what they're looking for. This, of course, is also very good for SEO. 
Do you have zero interest in an expensive mountain bike the company you are an affiliate of sells? Well, you probably don’t want to feature it on your blog, as it is extremely difficult to persuade readers (or anyone for that matter) that they should buy something you wouldn’t be caught spending a single penny on. When you are passionate about a product or–at the very least–interested in learning more about it, this will come through to your readers, engage them and better coax them to buy
Find work. When you first start out, you may have to accept work writing about a topic you don’t find all that interesting. You must keep an open mind and be willing to accept work that may not be in your desired field. However, as you continue to write, you not only learn about more topics, but you also build your reputation. With time, you can be choosier about assignments you want to accept.[19]
I'm just starting at Clickbank, so I'm a total newbie, but if I want to follow this strategy can I do it promoting just one product, for example, Category>Health & Fitness ---> X product. Then, should i start a blog or something like that where i can talk about things related to the product subject? if so, do i have to start making entries about this recurrently? or I can opt for just making an article with a free ebook in exchange to user's e-mails and follow the process?
Considering that you have a finite amount of time, passive income should make up a large part of your work. And if you're serious about generating any semblance of income online, then passive income should be one of your sole goals and ambitions. Why? Simply this. Wouldn't you prefer to do the work one time and get paid repeatedly as opposed to relying on your time to generate that income?

In the past, many affiliate marketers focused on a catch-all approach, offering traffic up to hundreds or thousands of sites, even if they had little authority or traffic to give. But in 2018, advertisers will laser their focus into smaller groups of highly credible, targeted, and popular influencers. To map your strategy, focus on a few key influencers in your industry. Start with them, then nail your niche before expanding outward.

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.