The page you are viewing right now is a content page, a product page, using the shoe store example again, would be a specific pair of boots.
Sites should have more content pages than any other type of page, so with enough content pages you should be able to target a wide variety of keywords and the traffic potential can be enormous. I sometimes refer to this as brute force SEO. With enough pages you're bound to rank well on some terms, and decently on others, so you'll receive a good deal of traffic purely as a result of the amount of content you offer.
Content pages in general are deep in a site's structure and so they are often harder to focus PageRank on. You can do it though. On my ecommerce site I link to my most popular individual products on the left menu. I want (and have) #1 rankings for these product names so I focus as much PageRank as possible on them by linking to them from every page of the site. You can do this with any site though. The new article listing on this site's homepage is focusing PR on the new content to get it established. An ecommerce site can do the same with a new product listing. Some ecommerce sites (mine included) also have a most popular product listing which reinforces the popularity of those products.
Just as with category pages, you basically want to add more links to the products you want to promote. Also as with category pages the more links to products you add the less weight you're sending to your homepage or category pages and so they suffer a little bit.
The on-page optimization stays mostly the same. You want keyword rich anchor text, usually the product or article title. You also want one page keywords, keywords in the title tag, and keywords in headings. Multi-page articles can be an issue though. You should not use generic words like "Next Page" when sending people to the next page of a multi-page article. Instead use a keyword rich phrase of some sort. Also, if the article is particularly long and you want to make sure to promote even the last pages of it well you should include a keyword rich table of contents at the beginning of it, otherwise PageRank is heavily diluted by the time it reaches the last page.
You don't need to pick one type of optimization, you can use a mix. If there is a particular product or category that is much more popular than the rest (according to your keyword research) feel free to give that one special attention, as I do. Just be sure you aren't wasting all your energy on optimizing the wrong part of your site. If you had trouble understanding any of the concepts in this article, or would like a more in depth explanation of some of them, please read the following related articles: