There aren't many qualifications to being president:
Age and Citizenship requirements - US Constitution, Article II, Section 1
No person except a natural born citizen, or a citizen of the United States, at the time of the adoption of this Constitution, shall be eligible to the office of President; neither shall any person be eligible to that office who shall not have attained to the age of thirty-five years, and been fourteen years a resident within the United States.
Term limit amendment - US Constitution, Amendment XXII, Section 1 – ratified February 27, 1951
No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once.
The only other is to win the electoral college vote.