There are many ways for teenagers to make money. Some ways will require more time and effort.
Babysitting: Ask family friends if they need someone to watch their children. Set a predetermined amount before watching the children.
Mowing lawns: Find neighbors who would like a little bit of help with their landscaping.
Dog sitting or dog walking: Many people do not have the time to walk their dogs. Set up a dog walking service. If a family friend is going out of town, ask if they need someone to periodically check on their animals.
Selling clothes: Some consignment shops pay money for used clothes if they are in good condition. There are also websites that allow people to buy used clothes.
Online surveys: Companies will pay money for an honest opinion. Research sites to find one that allows teenagers to take part in the reviews.
Part-time jobs: A teenager may be able to get a job at a fast food place or retail store. Teenagers must be age 14 or older to be hired. Check laws to see what rules apply in local areas.