Please note that some of the links below are affiliate links and at no additional cost to you, I will earn a commission. Know that I only recommend products, tools and learning resources I've personally used and believe are genuinely helpful, not because of the small commissions I make if you decide to purchase them. Most of all, I would never advocate for buying something that you can't afford or that you're not yet ready to implement.
Some merchants run their own (in-house) affiliate programs using dedicated software, while others use third-party intermediaries to track traffic or sales that are referred from affiliates. There are two different types of affiliate management methods used by merchants: standalone software or hosted services, typically called affiliate networks. Payouts to affiliates or publishers can be made by the networks on behalf of the merchant, by the network, consolidated across all merchants where the publisher has a relationship with and earned commissions or directly by the merchant itself.
Research individual companies in your desired niche: If possible, it’s always better to become an affiliate directly with a company (if they have an internal affiliate program), as no one else will be dipping into your commission rate. This is the preferred route for most of the prominent affiliate marketers, including Pat Flynn. Unfortunately, it’s also the most work, as you’ll have to do the research yourself to see who offers programs (they’re usually listed in the website footer).