I'll sum up the method for you. If I recall correctly, there was a Clickbank guide here that went over some of this, but I can't seem to find it (I think a moderator wrote it a while back).
- Sign up for Clickbank.
- Pick a product in whatever niche you're in. If you don't know how to choose a product, I've linked to threads that go over this below.
- Download the tools from the vendors affiliate tools page (if they don't have one, scrape the content from the vendor's landing page.
- Create a Blogspot blog and use the tools or scraped content to sculpt a landing page. If you don't know how, just download a landing page template from one of the sites I've linked to below.
- Go into Google News, type in keywords related to your niche, and visit the websites that come up.
- Promote your Blogspot website's URL in the comments section. It helps to write the comment in a way that doesn't make it seem like spam.
- Keep commenting on blogs until you make a sale.
Choosing a product:
http://www.blackhatworld.com/seo/how-to-choose-cb-products-for-newbies-a-5-minute-guide.688820/
http://www.blackhatworld.com/seo/tutorial-how-to-choose-clickbank-products-to-promote-for-absolutely-beginners.724675/
http://www.blackhatworld.com/seo/clickbank-how-to-pick-outstanding-product-and-make-money.799895/
Creating a landing page:
https://themeforest.net/category/blogging/blogger
http://devfloat.net/best-free-modern-blogger-templates/
This was a method I used back when I did affiliate marketing, which I no longer do actively these days, so I'm unsure of how well it would work now. Even back then, this method wasn't the best since it doesn't take conversion rate-optimisation (CRO) or any other marketing factors into account, so your conversions, click-through rate (CTR) and sales won't exactly be great.