Question about choosing keywords for amazon affiliate site

Hey,

I am a bit confused about choosing keywords, I have found couple of good keywords in the same niche, and let's say I have one main keyword "*** *** for sale" and 4-5 other secondary keywords like: "cheap *** ***" "best *** ***" and etc. Okay, I understand that I have to create a website around the main keyword, but how can I use the secondary ones? Should I write articles optimized for them? Should I create a different page for each of the keyword and rank those separately?

And how many secondary keywords is good to have?

Thanks in advance.

Create some posts targeting those KW's. Or you can choose to target a few of them on the homepage itself.