It is easy to become an affiliate to sell products; all you need to do is join someone's affiliate program. Joining an affiliate program does not cost anything. There are no minimums to sell, so you can sell at your own pace. When you join an affiliate program, you will receive your own unique id you use to link to products you are promoting. You make money by selling products.
There are many products you can sell online through affiliate programs. How can you pick affiliate programs that are right for you? Since you are already working with a target market for your virtual assistant business, I recommend that you pick products that appeal to your target market. It is much easier to sell products to an already existing target market than to start working with a completely new target market. Selling products to your current target market will help you create revenues in the shortest amount of time.