Ask HN: Starting a company blog, what should I know for SEO?

I am working on a SAAS startup and want to start posting to a blog for SEO and to refer our customers to our posts for information. What are things I should know for SEO? I think we are going to go with Wordpress.

Does it matter if it's blog.website.com vs website.com/blog? Does it help to have posts link between each other? Are there a list of meta tags I need to take into account? Thanks!