Decide specifically in which area of beauty you'd like to get your license. Whether it's nail care, hair care or massage therapy, you'll need to see if your potential future school has a program for that, and if the program is reputable.
Assess your life situation to determine which school will be right for you. If you're going to be working, the school will have to have flexible hours. If you're still going to live with your parents, then the school should be near home. Conversely, if you're going to be moving away, make sure the school offers student housing and determine whether that housing is affordable.
Make sure the school is accredited. There are a lot of beauty schools out there and some are more reputable than others. One organization that's been approved the U.S. Department of Education to accredit cosmetology schools is The National Accrediting Commission of Cosmetology and Arts. Look for this accreditation, or an equally valid one, when choosing your school. If you're unsure of the organization that the school has been accredited by, do some background research on them.
Check to see if there are hands-on programs available. Cosmetology is a very hands-on trade, and if the school doesn't allow students to practice their skills on mannequins or dummies before sending you out into the real world, it may not be the best school.
Consider the length of the program. If you feel that you need to get finished fast, look into schools that offer shorter programs. Don't sacrifice quality for time though. There's no sense in spending your money and time getting a degree from disreputable school.
Check to see if the school offers career placement options. These are programs built within the school that assist you in finding internships and jobs to help you start making money as soon as possible.
Find a student who attends the school and ask them about her personal experience with it. Getting to know a firsthand perspective may help more than any amount of research you can do online or over the phone.