Some of the easiest affiliate programs to get into as a beginner are those with minimal barriers. Amazon Associates is a great place to begin since they have endless amounts of products. ClickBank is another great choice for beginner especially for digital items. A few other people who's into affiliate marketing are using Etsy affiliate programs as well. Do you think you would prefer to promote common everyday products or to specialize in items like software, courses, or gadgets?
I began with Amazon Associates and then proceeded to ClickBank. Amazon was easy to get familiar with, and ClickBank provided greater profits especially with the electronic products.
I would prefer to go for those simple products as a beginner as they are easier to market. The preferred entry points for beginners are Amazon and Etsy affiliates.