Be honest. Talk about what you like and don’t like. Be fair and build trust. It will serve you well later. For examples, check out my review posts about Elite Blog Academy and Self Publishing 101. I get emails frequently from people who tell me they decided to purchase one of those courses through my affiliate link because it was the most balanced review they found.
Many affiliate programs run with last-click attribution, where the affiliate receiving the last click before the sale gets 100% credit for the conversion. This is changing. With affiliate platforms providing new attribution models and reporting features, you are able to see a full-funnel, cross-channel view of how individual marketing tactics are working together. For example, you might see that a paid social campaign generated the first click, Affiliate X got click 2, and Affiliate Y got the last click. With this full picture, you can structure your affiliate commissions so that Affiliate X gets a percentage of the credit for the sale, even though they didn’t get the last click.
If you’re writing reviews, you should 100% be using rich snippets (they add review stars to your search engine snippets and increase click-through rates). There are many WordPress plugins for this but my favorite is WP Rich Snippets. It’s $69/year (or $399 one-time) and I use it for every single review I write. They have tons of add-ons, settings, styling options, and looks nice. Free plugins like All In One Schema.org do work but lack settings, styling, and flexibility.
If the answer to each of these questions is a resounding yes, rather than jumping to conclusions immediately, take time to research whether or not others are out there making a sustainable affiliate income from products and content in this niche. In a sense, competition is a good thing here—it'll help you validate your idea and prove that it's worth of building a business around.