Blogging is one of the best ways to promote your website online! By writing a blog for your website, you give a reason for visitors to keep returning to your site and keep up to date with your latest posts. It also helps search engines to crawl your site more frequently, as they have to update your latest blog post entries, which ultimately helps you rank higher in search engine results pages (SERPs).
You need to produce and include lots of unique content for your blog, such as; Infographics, Top Lists, How Tos Tutorials, Viral Videos, etc. Try to remember to be clear and concise in what you are trying to convey to your readers within your blog posts, don't waffle.
To help you promote your blog, submit it to niche blog directories and blog search engines.
If you're not very good at writing content for your blog, then you could always hire a guest blogger for your blog and ask him/her to write precise and unique content so that your blog can gain more credit from a search engine point of view.