Complete your undergraduate education.
Although specific qualifications vary, all law schools require that applicants have completed an undergraduate degree. You certainly don't have to major in prelaw, but you will have to complete a degree in some discipline in order to be considered as a law school candidate.
For guidance on the kind of classes you can take to help prepare for law school, see Recommended Undergraduate Courses.
Take the LSAT.
Many college students considering law school take the Law School Admissions Test (LSAT) either the summer after their junior year or during the fall of their senior year; if you are no longer in college, you want to take the LSAT as early as possible before law school application deadlines approach.
For some tips on preparing for the test, see LSAT Prep in Three Steps.
3. Complete your legal education.
With few exceptions, you will have to earn a Juris Doctor degree in order to sit for the bar exam in order to become a lawyer. Degree requirements vary greatly by school, so be sure to read up on the specifics of any law schools you are considering.
For more information on narrowing down your choices, see 10 Criteria for Choosing a Law School.
Pass the bar exam.
Again with few exceptions, you will have to pass a state bar exam in order to become a lawyer. There are often many other requirements to sitting for the bar exam as well, which can include the MPRE (Multistate Professional Responsibility Exam), character references, and criminal records clearances, so be sure to check with the bar examiners in your state for specifics.
For more information on preparing for the test, see How to Pass the Bar Exam.