You can ask people in your area if you can help with any yardwork, walk a dog for some people, stuff like that, but make sure it's o.k. With your parents. Hope this helps, good luck.
As a pre-teen this is really something your parents should handle. If you live in a close small neighborhood ask your parents if it is ok for you to let people know you are looking to make some money. People need garages cleaned, cars washed, etc. Minor yard care where the equipment you use is not complicated or dangerous. Going to the neighborhood store is often needed. Whatever you do, speak with your parents before you see a job and be under their guidance. They will most surely tell you what would be improper acts or conversations. Trust your parents' words. When people know a child wants to work they make "make up" a job for you being proud you are interested in earning money instead of seeking it in a criminal way....Remember take your parents' advice. Be safe and I hope you are safely successful.
Baby sit or clean house