Create a content rich, informational site which is loaded with quality articles, tips, free advice, and tutorials, and keep your options to buy a product very subtle. The number one reason most people go online is to look up information, so the key is to discover high-demand topics for a niche audience and give your audience exactly what they are searching for first. Satisfy their search first and then offer them the option to buy.
When working on your content remember to “flesh it out” in the re-write process with a few additional synonyms of your focused keyword phrase. You want your article highly focused on your topic, but it should not sound Spamy with the same keywords repeatedly used in an un-natural way. Google loves to see synonyms and antonyms and descriptive related text used in your copy so that your content reads well to a human being.