The home page of your site is usually a good place to start. It typically holds a wide array of information about your product or service and will lead the website visitor to where they want to go. However, if you have other informative pages on your site that you think would be more helpful, you may want to choose one of those pages in addition to, or instead of, the home page.
Organic search should not be viewed as just one of many different marketing strategies. Instead, it should be the cornerstone of your efforts. Your materials should all be optimized to maximize their appearance on the SERPs. You should also be using the insights that can be gleaned from organic search to inform the rest of your marketing endeavors.
Remember when you used to rely solely on search engines for traffic? Remember when you worked on SEO and lived and died by your placement in Google? Were you #1? Assured success. Well, okay, maybe not assured. Success only came if the keywords were relevant to your site users, but it was the only real roadmap to generating site traffic and revenue.