To increase search result rankings, you need to increase the relevancy of your web pages. But, relevancy to what?
Relevancy to Keywords
If you just want to increase relevancy to search keywords, there is software that does that for you. When you type keywords into the software, it will create a list (not a meaningful article) stuffed with keywords you specify. Some software even inserts links with key-word-rich anchor text, so that you can crank up the PageRank of the site the fake links are pointing to. These cheap techniques might increase your pages' rankings. However, you won't be able to increase sales with those useless web pages.
Relevancy to Objective
If you want to increase your sales, you need to increase the relevancy to customers' objectives. For example, for people looking to buy a telescope, articles about good and bad telescopes are helpful in choosing one. When you help customers to get their jobs done, they will decide to buy from you. To sell more products, you need to focus on customers' goals rather than focusing on your goal (tricking search engines).
Ranking Isn't Everything
Moreover, to be at the top of search result pages isn't that important. Searchers will go down the list of results until they find useful articles. How many worthless web pages show up on search result pages is search engines' problem. What's really important to you is to stand out from the crowd with quality content.
© May, 2011