Hands down I’d say the best thing you can do is research 1 primary keyword, craft an enticing article title that includes your keyword (though it doesn’t have to be an exact match), spend time writing your search engine snippets (SEO titles/meta descriptions), and by far the most important is making your content as VALUABLE as possible through videos, nice graphics, table of contents, bold/colors/styling, etc. Small things like keyword density barely matter.
Will my target audience realistically spend this amount for the product? Again, your reputation is on the line here. Is the product you are thinking of promoting priced reasonably for your audience? When I was writing my ebook, I was stuck on pricing. I asked around for opinions. A number of people suggested I price my ebook at $47! Their idea was to price according to value, not size. In my mind that was crazy. My network was composed of a lot of stay-at-home bloggers, and my collective audience was comprised mostly of people without a whole lot of disposable income. There was no way anyone was going to pay $47 for my 30-page ebook.
I would like to add that for information products, a lot of the time it’s pretty easy to rank for “information product review”. I recently did a review of a popular ebook that is a month long discipline program. I went about it by doing the actual program and documenting everything. At the end of the month I wrote up a 2700 word article summing up the whole experience.
However, be aware that you need to submit an application to most of these networks to be accepted. Once you're accepted in, you're often required to apply directly to the merchant afterwards. So there are two layers or gates that you need to bypass. That's also why it's important to build up your platform and create that emotional bridge between yourself and your audience before attempting to promote anything to them.

Pins with affiliate links should have an FTC-compliant disclosure that makes it clear that purchases made through that pin will result in compensation to the original pinner. Publishers should also confirm that the advertisers they’re working with allow their affiliate links to be posted to social networks so they don’t violate the program terms within that relationship. It’s best to read and follow Pinterest’s Acceptable Use Policy.

Hi Kate, on Pinterest, you can add the affiliate URL when you create the new pin on your account. If you already have the pin made and want to add the affiliate link, you can just “edit” the pin and change the URL. Hope that makes sense. In the book, Elise has a step by step tutorial with photos on how to add the URL to Pinterest in case you need more help.