You cannot practice law or call yourself an attorney without first meeting the professional requirements for becoming a lawyer. These are numerous and range from meeting educational standards and performing successfully in a bar exam, to clearing moral character and background checks. Below is a comprehensive list with descriptions of the standard prerequisites for the practice of law.
Understanding what is required of lawyers before they may legally practice law may help you find a qualified attorney (or decide whether or not to enter the legal profession yourself). See FindLaw's Guide to Hiring a Lawyer for related resources, including Researching Attorney Discipline and State Bar Associations.