Internal link from the blog, that way people can browse and read similar posts. Link with relevant keywords (I like using a plugin called Blog Mechanics Keyword Link Plugin v0.3.1 | BlogMechanics to link to the client's site).
Use the sitemap generator, and expand the ping list for the blog to ping absolutely everything whenever a post is published. Submit to RSS directories especially, and a few blog directories. Choose a template that's
SEO friendly (wordpress' default template titles things Blog Title > Post Title) or if you're really keen, use the All in One
SEO plugin.
For blogs from businesses though you can get away with more, and you should really try and build a community around your blog, which will then go through to your client's businesses. Comment on blogs that are in the same niche, or in the same local area as the business (obviously not so if it's an ecommerce site!)
or
Use all in one
seo pack plugin if you use Wordpress. This is good plugin to optimize your blog title