Re: Blogs, links, and Keywords - Do they matter?
A subdomain is not really treated as a separate domain. It inherits authority, page rank, branding, etc., from the main domain, just like a subdirectory. Indeed, on the actual server a subdomain physically is a subdirectory off the main domain.
I'll prerequisite this with the fact that I have not personally done this in quite some time. In speaking to several people in recent years who were more familiar with it then I was, I've heard the same as Eric, sub-domains are treated as separate sites, therefore, requiring separate SEO initiatives for each sub-domain. Sub-directories/folders are much easier to pass along link juice and require 1 SEO effort. I was always told that sub-domains are okay, as long as you have the resources to manage multiple SEO initiatives or if you have a separate part of the business that has little relation to the business of the main domain.
Djbaxter, have you read sometime recently that sub-domains are treated as you say or have you worked with a sub-domain recently? Perhaps this has changed and sub-domains are not treated individually anymore. I'd be interested in hearing more about your experience with this, as long as you don't mind sharing.
This is a discussion from Feb 2014 on Moz where Rand himself chimes in
Moz's official stance on Subdomain vs Subfolder - does it need updating? | Moz Q&A
I only have a little to add to the quality comments already made. I always say, Google or Bing is not buying your service or product, humans are. Make your content speak to your audience. Make them easy to read. Blogs are one of the easiest ways to add fresh, unique content to a website. Earning links is a lot more difficult then it sounds. You should internally link to other pages on your site only when necessary and not only for the sake of it. It's said that linking early on, in the 1st paragraph is usually best.
Social media sites such as FB, Google+, etc. should give your content legs. Use your blog as your hub and to get your content in front of your readers, prospects, etc. Don't forget, content is not limited to articles. Images, video's and infographics are also great forms of content to attract visitors and keep them engaged on your site.