To start the earning from the affiliate marketing, you need to have your own website where you can add affiliate programs for the users.
There are many affiliate's programs offered from e-commerce website's and other big brands. Only the eligibility criteria change from company to company.
Some Website's First verify your website and then approve it. Some Affiliate programs put the minimum daily traffic. Some programs such as Amazon affiliates offer with the no minimum traffic criteria.
If you want to increase your website traffic and improve affiliate earning, you can hire a digital marketing services consultancy or make it on your own.
If you want to get success in affiliate marketing you need to update your website regularly with the fresh and unique content. Blogger website's such as Technology Blogger, Travel Blogger and many can optimize the website for affiliate programs more easily.