Most companies have a blog. Not because it's fun, or they have nothing else to do. It's because it's a great SEO and marketing tool. It will help keep your site updated. Google loves updated sites. There are probably millions of neglected and abandoned web sites out there. Google doesn't pay as much attention to those. That is why search engines are continuously checking the time stamps on when web sites are updated. Publishing blog articles is a great way to update your site frequently, and lets search engines know which sites are being cared for and should send its users to. A brand new website post even every few weeks will show the search engine bots that things are happening on your site. Maintaining a blog will allow you to start writing content related to those keywords you would like to rank for.
Write good content. You don't have to be an amazing writer, but try to write at a quality level that your visitors will want to stay around and read it. It increases the number of pages on your site. Again, write content that is related to the keywords you want to rank for. This is all the real key to SEO. The more content you have, the more the search engines will need to crawl and index. This helps give the crawlers a better idea of what your site is all about, and which searches it should rank higher for.
A great tool to help you write better is Grammarly.
Social media and newsletters
When you create a new blog post, share it on social media as well. Facebook, Twitter, Google+ and more. Send the posts out as a newsletter. This all works together and gets more viewers keeping you in the back of their mind. This helps promote your website and blog posts and reach an even further audience. People may not always go to your website every day or every week. This is a great reminder to your clients and potential clients that you exist out there and to come check you out once in a while.
To summarize, if you don't have a blog on your website get out there and do it. Write about your products if you're an e-commerce store. Write about your brand. It will pay off and Google will love you for it.