Article marketing is quite an ambiguous concept. When you’re just starting out, the general advice seems to be to write an article and submit it to as many directories as possible. In other words, focus on quantity, not quality. Add article spinning to the mix and article marketing seems to be only good for low quality links for SEO.
Others who have honed their article marketing skills will say you should only submit high quality articles to a few high quality directories. But you can only get so much traffic from a couple of directories. Unfortunately most advice on article marketing I’ve read in most sources ends here.