Nearly half of all students apply to college as “Undecided.” Many of the students who indicate a major will change it at least once before they graduate. At 18 years old, you probably have not discovered who you are or what you want to do with the rest of your life.
To quote Steven Covey, author of the widely popular series, 7 Habits of Highly Effective People, “Begin with the end in mind.” Make sure you are applying to colleges that have programs and classes that truly interest you. Once you get to college, if you are successful in those areas, you may be onto something. Spend some time thinking about how you want to spend your days once you are out of college.
The Bureau of Labor Statistics has a great online “Occupational Outlook Handbook” that offers descriptions of the training and education needed for hundreds of different jobs, as well as the earnings, job prospects and job descriptions for each: http://www.bls.gov/oco/
It’s fine to be “Undecided,” but you might want to start taking some steps to find your true calling.