Amazon can be very lucrative if you know how to use the affiliate program to your
advantage. You have to find good products to promote, do your keyword research
well and create content that gets the click. You must create a useful site for the
searcher, you can't just copy Amazon product descriptions and expect to have a
high converting site.
Comparing and rating products is a good strategy for an Amazon niche review
blog. Keeping your topics tightly focused makes for better SEO. Build one site
about grills, another on cat toys, for example.
The more tightly focused your products for each site, the better rankings and
conversions you will see.
Amazon gives you all the information you need to succeed as an affiliate marketer
for their products. They have millions of products, you can literally spend your
whole life building niche blogs to promote Amazon products and never run out of
things to sell.