The layout of your web site is a huge part of your seo ranking. You should ideally have navigation at the top of the page and second best would be left side navigation. When Search Engines spider the web they are looking for the most important information first. In this case it would be navigation, and content. The size of your titles and subtititles can also make a difference.
You do not want to have the "keywords" taking over your website. They should only be between 3 and 5% of the content on your site. Another tip is to make what the user is searching for easily found on the page. You can do this by having it at the top of the page and/or making it bold. Having a site that is relevant throughout is going to get way more points than a website that has many pages about different topics.
A great way to enhance SEO is to use social media such as blogs, twitter, facebook, and pinterest to get users coming to your page. The more often you blog, tweet, or status update about your site the better!
Social Media plays another important roll in SEO, basically the more people that like, follow, or pin your web site the better ranking you are going to have. Social Media is still evolving and taking shape in the online marketplace so it is ever changing. Source