Host Your Blog Directly on Your Domain
Hosting your blog on a different domain from your primary site is one of the worst mistakes you can make. A blog on your domain can attract links, attention, publicity, trust and search rankings - by keeping the blog on a separate domain, you shoot yourself in the foot. From worst to best, your options are - Hosted (on a solution like Blogspot or Wordpress), on a unique domain (at least you can 301 it in the future), on a subdomain (these can be treated as unique from the primary domain by the engines) and as a sub-section of the primary domain (in a subfolder or page - this is the best solution).
Tags: blog, Blogspot, different, Directly, Domain, Host, keeping, mistakes, primary, subdomain, subfolder, WordPress, worst