I found a very useful and informative blog a couple of months ago called CopyBlogger, http://www.copyblogger.com/ . It's already taught me so much about online marketing, developing engaging content and attaining maximum SEO results. I have yet to find a blog as informative as copyblogger, and believe me, I've been looking! It even provides free training courses that you can sign up for. You can download individual articles in pdf format to print out for future reference.
As an online entrepreneur, I'm always looking for ways to learn from the best in order to build my business, exposure and profits. So far, copyblogger is my go-to site for training in online marketing, whether it's a product or myself (which really is a product, isn't it?). I signed up for their feed so that I don't miss anything--and feeds are something that I subscribe to VERY selectively, seeing that I get probably 50-75 emails a day.
I hope that this helps..