Know when (and when not) to use Viglinks and Skimlinks. If you applied to an affiliate program but were denied, you might be able to still be an affiliate for that advertiser through a secondary affiliate program like VigLink or Skimlinks. Basically, they themselves are affiliates and will split their affiliate commission with you if you put their affiliate link in your content for an advertiser. Obviously, the commission rate is lower for you in this case, so if you ever are accepted into the advertiser’s affiliate program directly, immediately switch from using VigLink / Skimlinks affiliate links to your own.
Become an Amazon Associate and then use Keyword planner to find an in-demand niche: With more than a million different products to choose from and up to 10% commission the sales you drive, Amazon’s affiliate program is a great place to get started. Browse their available products and see what connects with you. Or take it a step further and use Google’s Keyword Planner to quickly check how many people are searching for a specific term. With affiliate marketing, the more relevant traffic you can pull in, the more you’ll make off your site.
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.