First, consider geography. What region(s) of the country are you considering? Do you prefer schools in cities or college towns? Are you including schools in the region where you intend to practice law? These considerations may seem trivial, but they can have a significant impact on your law school experience and even your employment prospects. [Note that geography is not as significant a factor if you are considering law schools ranked in the Top 14 because these schools have strong national reputations.]
After identifying certain state(s) or region(s), you should narrow the list of schools in those areas by considering the schools’ admissions criteria. When applying to law school, the most important two pieces of your application are your GPA and LSAT. So you should find out the following for each school you are interested in: (1) median GPA/LSAT, (2) 75th percentile GPA/LSAT, and (3) 25th percentile GPA/LSAT. Consider choosing a range of schools to apply to, including 2-3 “target” schools (where your GPA/LSAT = median GPA/LSAT), 2-3 “reach” schools (where your GPA/LSAT < 25th percentile GPA/LSAT), and 2-3 “safety” schools (where your GPA/LSAT > 75th percentile GPA/LSAT).
Other important information to consider includes the employment statistics for recent graduates of each school that you are considering. The American Bar Association collects and publishes this information at http://employmentsummary.abaquestionnaire.org/. Of particular importance are the percentage of recent graduates who are employed as full-time practicing lawyers within 9 months of graduation and, at the other end of the spectrum, the percentage of unemployed graduates who are still seeking employment 9 months after graduation.
Before actually committing to attend a school you should also consider the cost of attendance, but you cannot be sure of your actual cost of attendance before knowing if you will be offered merit- or need-based financial aid. But by applying to a range of schools, including target and safety schools, you are more likely to receive an award of merit-based financial aid from one or more schools.
For a great in-depth analysis of these factors, check out this one by Law School Transparency.