Matt Cutts confirms that responsive design strategy doesn’t negatively affect SEO results, assuming the site content is rich with content and it loads fast. He overviews well in this video the two options for mobile development: developing a responsive deign or developing a separate mobile web site that is launched automatically when the user accesses the site with a detected mobile device. An additional option is to offer an iOS and Android apps.
This SEO infographic makes several good points and reminders on how to optimize a web page for higher SERP. A well optimized page is a synergy of optimal code and properly planned out titles, text content and linking. An engaging content that keeps visitors on the page reducing bounce rates is highly important for reaching higher search engine ranking results.