Selected answers from the Dumb SEO Questions G+ community.
Yuliana Kronrod: “Buy + product name + (optionally) online“ key phrases tend to convert at a higher rate
Jason Mun: Really depends on the niche of the website. 9/10 times, the biggest traffic drivers and high converters would be your product category and sub-category pages. If the website is selling products from other brand and manufacturers, then the brand pages would also be great traffic and conversions.
Looks something like this once you have done your keyword research and keyword mapping.