What you get out of a job like this depends on your attitude. If your attitude is "I hate this job" then obviously you won't benefit much from it; if, on the other hand, you look at it as an opportunity to learn how a business works from the inside out, then the benefits can be great. Many of the new generation of millionaires, for example, are owners of franchise, and it requires knowledge and skill to be successful, so start gathering this as a teenager. Try as many positions as possible and ask lots of questions about cash flow, staffing, etc. Applying this attitude to any job you have will really pay off, you' learn a huge amount.
For many teenagers, there are a variety of problems associated with getting a job. You may not be old enough or you may lack reliable transportation. You may not have enough total time available or a regular enough schedule for someone to be willing to hire you. You might not even be able to find a job in an area that you enjoy. If any of these problems holds true for you, then working for yourself on a part time basis may be the best way to go.
Baby-sitting, for example, is a tried and tested way for responsible teenagers who like being with kids to make money. There are several things you can do to make your services more valuable. Think about taking a first-aid course so that you know how to handle emergencies. Secondly, you might want to consider teaming up with some like-minded friends. That way your group will be able to say yes more often, increasing the amount of work you're offered.
One question you will have as soon as you choose an activity is "How...