Dear Sir,
I had come across a job in Data entry, which you have offered. I have some experience in this field and had been searching for a job in the same. As you are also looking for similar work to be done for you, I'm quite excited to find this offer and would like to gain some work experience from this job. The reviews given for you have also been so encouraging for me to submit my proposal and work with you. It would be so welcoming for me to start my work with a client like you and also gain some knowledge further. Hope you would accept this proposal and let my first job experience make worth for me to have worked with a client like you.
Awaiting your reply,
Thank You