The above three give you cash, but many merchants give you store credit. Examples of those would be Stitch Fix, thredUP, Zulily, The Honest Company and more. Whether those would be worth it to you will be dependent on how much you shop there. Stitch Fix will give you up to $600 a year in referral credit. That's $600 worth of clothes that I don't have to pay for. That's worth it to me. Once I hit that $600 mark, I switch out the link for their Commission Junction affiliate link so I am still earning on any signups after I hit their referral threshold.
Affiliate marketing is basically performance-based marketing, whereby affiliates/partners promote a merchant’s product/service and get remunerated for every sale, visit, or subscription sent to the merchant. The most frequently used payment arrangements include: pay-per-sale, pay-per-lead, and pay-per-click compensations. Affiliate marketing is one of the most powerful and effective customer acquisition tools available to an online merchant today. You decide what commission to pay, and pay only when results (sales, leads and/or clicks) are obvious.
You should also make sure you aren't competing with your own affiliates for eyeballs. Any marketing channels you're using, such as search engines, content sites or e-mail lists, should be off limits to your affiliates. Put marketing restrictions into your affiliate agreement and notify partners immediately. It's your program--you set the rules. Or, if you prefer, you can let your affiliates run the majority of your internet marketing.