Go to
this site and take the Self Directed Search. It will cost 9.95USD. The result will be a report that will give your career preferences score on six dimensions: Realistic, Investigative, Artistic, Social, Entrepreneurial, and Conventional. The top three scores give you your Holland profile. Holland's theory says that you are likely to be happiest in careers that more or less match your profile. It will give you several lists of possible career choices, starting with the best matches. How does it match? The SDS runs on a database of many thousands of test results, and they've matched actual career satisfaction with a person's Holland profile.
So this will give you a list of careers that people with similar Holland scores have been pretty happy with. Now what? You can investigated each career on the O*Net online site. Look at your report (or the sample report on the site): each career listed has a DOT Number associated with it. Go to the O*Net site
here and enter the DOT Number for the career you're interested in investigating in the field "DOT code or title search". This will give you all kinds of interesting information about the career, including education needed, job prospects, skills needed, median earnings in the USA, etc. You can even get a report tailored for a specific state. (this is all based on U.S. government data, so bear in mind that if you're in a different country the situation may be different there)
Note that this doesn't tell you that you'd be good at something, but it does tell you the sorts of careers you'd likely be happy with given your preferences.