Maybe you're not sure. Then, it's time to research. The internet makes it easy. There are a wide variety of excellent sites in which to begin researching occupations. There's also your public library.
Many libraries have excellent career research sections.
Ask your librarian for assistance. This leads to networking. Networking is not only for people who are actively looking for a new employment situation, but for people who want to learn more about different occupations. Informational interviewing is the act of gathering information through personal contact with someone working in a field you're interested in. Networking is then asking everyone you know if they know of anyone working in a particular industry, until you find someone who knows of a position that's available.