My favorite response is ask google Google webmaster tools, gives a comprehensive listing of everything you need
to make yoursite SEO current, any time the algorithms change, free, personalised, from the ones who make The_Rules
get a google webmaster account, Its Google doing most of your SEO for you
User friendly and responsive design website. Add unique content in the website. Proper url structure(use hypen and avoid other symblos), add all meta tags, image tags, heading tags, adding keywords in title and description. Try to integrate all social networks i you website.