Determine a state, or at least a region, in which you'd prefer to live and attend school. New York and California have the highest concentration of fashion design schools. They are the "fashion centers" of the U.S., but they are also expensive places to live.
There are other plenty of other fashion design schools across the country. Geography, for some people, is a strong determining factor. For example, you may need to live with your parents or other family members to save money. However, your decision may ultimately be based on program types, the reputation of the school or where you ultimately want to work.
Decide on a budget. The cost of attending fashion design school can vary widely. You may qualify for scholarships, depending on your previous grades and portfolio, which is an important factor in your acceptance to a design program. Find out if you qualify for federal grants or student loans and evaluate your savings and any potential contributions from parents or family. Make sure you choose a school that you can afford, because starting salaries for jobs in the fashion industry are often low, and you don't want to be saddled with loan debts that you can't afford.
Consider the aspect of fashion in which you'd like to focus in design school. Aside from straight-up fashion design, you may choose to study fashion marketing, merchandising or retail management. Or you may choose to focus on a particular facet of fashion design such as shoes, accessories, costumes design or textile design. Some schools are known for their program specialties, so this may be a strong guiding factor in your choice.
Check the National Association of Schools of Art and Design (NASAD) to see if a school that you are considering is accredited, to ensure that it holds a high standard for its courses. Consider the reputation of faculty members as well as famous or successful graduates from the school. Find out if you will have access to an alumni network or if the school offers job placement services. In the fashion industry, success often rests on 'who you know.'