One possible version:
For me, a friend is someone I can depend on and I love.
When I was eight years old, I met my best friend, Li Mei. Her personality was different from mine. She's very active and brave. When I was sad, she would sit next to me and comfort me. When I was happy, she could share my joy. What's more, she always encouraged me. She advised me to have another try if I wanted to give up halfway.
So far, we have been friends for eight years. Although we were not classmates anymore, I believe that we'll still be good friends forever. What's more, I will prepare a birthday party for her to give her a surprise.