Frankly I find the practice of re-writing to be absolutely worthless. If you write a single good article, use some distribution method to hit up a bunch of directories and see who picks it up. Article marketing is about attracting high quality high interest buyers to move products. The SEO benefits of rewriting are marginal and the traffic benefits of rewriting compared to submitting the same thing all around are non-existent. Write good articles and find a way to get traffic to them, such as using social bookmarking to drum up some support. In regards to resubmitting a re-written copy to the SAME article directory, that is disrespectful to the company and frankly to your own name as an author. Integrity always has been results in the long run despite the quick profits to be made in the short run.
I've made some money with article marketing. In my opinion working on the top directories would be the best. The more unique articles to them the better. Also with sites like ezine you only need 250 words a piece. Instead of writing long article write smaller ones with multiple parts. This can help when looking for more topics. Outsourcing is great in the long term. For SEO remember to outsource all types of works for back links. Forum posting, blog commenting ect. By no means am I an expert just trying to learn and get better like the rest.