Hi Nancy - see my corrections below. Overall, there are barely any mistakes and I can see that your writing has improved a lot, well done. If you have any questions, pop me a message and, as always, best of luck with the competition.

Tom

I‘m best at being me

(singing) Doctor, actor, lawyer or a singer? Why not president, be a dreamer? You can be just the one you wanna (this is slang, so maybe consider saying "want to) if they are strict with slang) be.

I have always dreamed of being a volunteer. Last year my friends and I thought of an idea to do volunteer work for Earth Hour. We planned to publicize Earth Hour and gave some paper cranes with our slogan on it to the passers-by as a promise of supporting environmental protection. However, based on the consideration of our safety and study, our teachers and parents were opposed to our idea. I thought about it for a long time and decided to insist on my own idea. At last, we made it! We received support and responses from lots of passers-by, and led them to pay more attention to environmental protection.

In this activity, I followed my heart. I didn’t let anyone affect my correct judgment, because I knew what I wanted, and the meaning or the value of every decision that I made.
I think I’m best at being me and staying true to myself. I would will (because it is not hypothetical or conditional) always try my best to achieve my dreams, and make you proud of me.