Babysit,Mow Lawns,try applying for a Paid Internship maybe(although I'm not sure if you have to be a certain age or not)-Ask neighbors if you could clean their garages or something around the house for cash. Walk Neighbors dogs, babysit peoples animals while they go on vacation.Post Flyers everywhere not just your neighborhood saying what you can do and I'm sure someone will give you something to do.
My daughter who is now 16 but has been earning money for 3 years. She cleans an office for a local attorney once a week. She also helps various neighbors (neighbors we know well). For a couple of years she would look after two little kids while there mom was there, so she could get things done. She helps an older lady with chores. Shes always been able to make money.