start go through reddit, Google trends and social media like facebook to find the new trends. Even notice the top competitor blogs effectively for some days. Then, you can have some idea regarding your niche.
First chose good well know niche. then optimize the on page
Not only good article, backlinks, web 2.0, But not low competition high search volume keyword play an important role.
Regular update your website to boost. But be patience to do your making process for promote your site.