There is no golden ticket that will shoot your site to the top of the Google rankings. It's as simple as that. I would proceed with caution if any company or freelancer guarantees SEO success, unless of course they are offering a 6 or 12 month plan.
Responsive design. It's all well and good. Your site adjusts to the screen size, and your users get a good mobile experience, without having two or even three separate websites. But the process for making your site truly "mobile friendly" is a bit more complicated.