Dear
I have read your job description carefully.
I am glad to present my connect for your job.
I understand you will hesitate to hire me since I am a new freelancer.
If you give me a opportunity to work with you that is my great pleasure. And everything will be OK.
I have a strong sense of responsibility and also detail-oriented.
I have a enough experience of Python Developing including Djiango, numPy, package developing.
So you think I am the best candidate.
Best Regards.