I have an article that might help you.
You must first do some keyword research. IF you don't your work will not get read because people will not be able to find it.
Then you must also write in a manner which will make the person desire the product or service you are writing about so much that they go buy it from a link on your article.
I do not personally sell products through Amazon, but I would say that the method is still the same.
Read this article to get a better understanding of what you need to do in order to have your work found by internet searchers.
If you do not use a keyword tool you will stand a very little chance of being seen.
You can use the advice of Peter to find a free keyword tool.