Dear Sir/Madam,
This letter is to express my interest in this position, announced in the job listing at Freelancer.
This position, particularly caught my eye, as I was scrolling through the jobs section.
I have a strong writing background and have worked for various sites such Hirewriters and Crowd Content. I earned a reputation among my clients for ensuring product satisfaction, and I would be happy to supply a list of client references.
I would very much enjoy discussing the possibility of our working together. I look forward to hearing from you.