Writing articles and submitting them to directories is one of the best methods for search engine optimization and driving traffic to your websites. There are some key tactics you must use to be most effective:
Vary your anchor text with the largest directories. I recommend changing the anchor text and layout of the links in your resource box for the top 4 article directories:
ezinearticles, goarticles, articlecity and articledashboard.

This will get you the best results as these are the sites that most people take articles from. Watch your conversion for which site directs the most traffic to you, and use that resource box for your widespread distribution.
Keep your articles between 400 and 600 words. Any shorter is not effective. Any longer can be OK in the right situation, but don’t write a book. Use words that are easy for everyone to understand.
Write about what you know. If you are in a niche that you don’t understand, outsource the writing of your articles. You can find freelance writers all over the internet.
Submit a few articles per week and you’ll find that your reputation will spread very quickly. I still receive phone calls regarding a niche that I conquered in the past. You’ll find that helping people will generate a level of trust that you can’t get elsewhere.