I don't think these days things such as keywords have a considerable impact on your ranking, although for sure having good keywords and following all the SEO basic best practices will help you be at the top, if the content you offer is great quality and relevant. If you think about it Google must spend a lot of resources in being able to spot just that, and they've been doing it for many years, no less than Google. Many years ago they used to rely in a lot less robust mechanisms than they use today and you could trick it to rank you higher... These days you're better off playing by their rules so I bet Google's guidelines on SEO are a great start.
I copied the following from that document:
Things to avoid
Don't fill your page with lists of keywords, attempt to "cloak" pages, or put up "crawler only" pages. If your site contains pages, links, or text that you don't intend visitors to see, Google considers those links and pages deceptive and may ignore your site.
Don't feel obligated to purchase a search engine optimization service. Some companies claim to "guarantee" high ranking for your site in Google's search results. While legitimate consulting firms can improve your site's flow and content, others employ deceptive tactics in an attempt to fool search engines. Be careful; if your domain is affiliated with one of these deceptive services, it could be banned from our index.
Don't use images to display important names, content, or links. Our crawler doesn't recognize text contained in graphics. Use ALT attributes if the main content and keywords on your page can't be formatted in regular HTML.
Don't create multiple copies of a page under different URLs. Many sites offer text-only or printer-friendly versions of pages that contain the same content as the corresponding graphic-rich pages. If your site has identical content that can be reached via different URLs, there are several ways of indicating the canonical (preferred) version of a page.