Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs.
There is also Facebook, Instagram, Pinterest, LinkedIn, and Twitter training for those that want to get social reach. There is paid traffic training, using PPC channels like Facebook Ads, BingAds, and Google Ads. And you can even get help creating and operating VIRAL campaigns which can happen if you create your content in a specific way. This can be a powerful approach as well.
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.