First of all you should connect your google analytics and webmastertool. Then use online-tools like moz / spyfu / similarweb / seositechecup just to know are there any problems with your site/SEO. The next step is to fix those problems and then start creating new content (do not forget h tags, links to other sites or your excisting content etc.). Here is a lot of work to do first before you could start moving forward with your SEO. Good Luck