Affiliate Marketing Secrets

Have started affiliated marketing of e-books about relationship and sexuality since October 2009. Till now, have problems in converting traffic into sales. I rely heavily on article marketing, till date, I have submitted over 200 articles on various sites, one of which is at ezines. I post 3 articles a week. I have also created a blog and it now has over 300 postings and have a daily traffic of over 300 visits. I have also signed on social networking sites, forums and also ping my blog regularly. I have signed up for back links or reciprocal links on various directories. Till now, my sales are very pathetic.I can’t even more than US$100 per month and sales are very sporadic. I have paid close attention to using keywords such as choosing those keywords which boost a monthly search of at least 500 on my headings and 1st few paragraphs of my articles.
I’m not sure what went wrong. I have been doing things very diligently, consistently and in a very disciplined manner.
I need some advice in how I can successfully convert the traffic to my sites into real sales as well as any other advice on how to turnaround my situation. Thanks for your advice and suggestions.