Blog And Article writer wanted

I am looking for someone to write blog posts and different articles on different niche. Blogs can be 500 words or more? longs but must have good keywords and well researched. These blogs will be used in adding to current websites. Subjects would be back pain x5 and Stress and Anxiety x3 per month Articles mainly will be used to promote the websites so they should be unique and with good keywords about 800 words long if possible. I am looking for someone to do this on more long term so the right person will have a contract for atleast 6 and will be writing various blogs on different niches.