Choosing an affiliate product or service to promote needs to thoughtfully done.
If you promote something to someone who has no interest on it, you risk losing credibility and having them request to be taken off of your list.
If you do it carefully, on the other hand, you will be successful and earn a steadily increasing income from affiliate marketing.
When I first started making money on the internet, it was by promoting affiliate programs and services of the people I had studied with.
If it was someone whose course or program was well done, delivered what it had promised, and helped me to move along with my learning of how to build my online business, I became an affiliate and promoted the programs to others.
This was before social networking was as big as it is now, so the only way to promote these programs was by article writing and marketing, blogging, and commenting in forums.
I could have also used Google AdWords, but I was not working at the time and had more time than money.
Today it is very different, and with sites like Twitter and Facebook, it is much easier to promote affiliate products and services.
I am still active in several forums, and find that connecting with people directly is still the best way to earn money.
You will also want to visit sites such as Clickbank, so you can search for digital products to promote.
I do this almost exclusively with article marketing, and have made thousands of dollars in small niches that are searched for quite a bit.
It is best to choose products that you are knowledgeable about or have an interest in.
This makes it much easier to write articles to promote the products, and more fun as well.