I think you have done an excellent job with your website. I found it very easy to understand and navigate. You break down the categories well.
The only thing I saw that I didn't like was when I tried to preview an article. It was hard to read and the window scrolled way too quickly. That made it hard for me to read. And therefore I couldn't tell how good the author's English was. And if I can't tell how well the author writes in English, then I certainly would never buy an article.
So, if I was you I would fix that. Make it easier to see a preview of the article. Make it really easy to read the preview. Other than that, I think you have done an excellent job.
