If you already have a website or blog, look for vendors that offer related but noncompeting products and see if they have an affiliate program. Stick to familiar products and brands—they're easier to sell. To promote them, place simple text or graphical ads in appropriate places on your site, include in a blog, discussion forum, or mailing list links to purchase products that you review or recommend or create a dedicated sales page or website to promote a particular product.
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.