One important consideration to make, is that the 100% free path of affiliate marketing can take considerably longer if you are interested in building a career. It is advisable to at least invest some of the money you make in an autoresponder service to take advantage of the sales funnel method; if you do not wish to invest in and maintain a website in the long run.
Choose a niche and a product to promote. Choosing a niche may be especially important when you are building your affilaite business for free as your ability to use your knowledge of the product and the language you use will be essential in driving a sale when you are completely reliant on organic traffic. In case you do not know, a niche is a more specific categorization of a product within a broader category. For example, ketogenic diets would be a specific niche of the broader diet/health categroy.
Utilize a free website building tool such as Wix.com, or a free blog builder program such as Google Blogger. Use these tools to build a free website or blog that is centered around the product or service that you have chosen to promote. Fill your website or blog with informative material and then add the affiliate links to their respective pages. You can consider making a more complete website using Wix and then using a separate Google Blogger page as a complementary means of organic traffic generation; as Google Blogger pages tend to have positive rankings in Google searches.
If you begin making some income, although still do not wish to make any large investments into, consider making incremental investments into facebook ad campaigns or pinterest pins to accelerate traffic towards your pages and affiliate links.