Donald Miller graduated from the University of Wyoming in 1984 with a Bachelor of Arts in English. He graduated from the University of Wyoming Law School with Juris Doctorate in 1987. He then went into private practice in 1987 and also clerked part time for the Federal District Court, for the District of Wyoming from 1990 to 1992. Don became a partner in Graves, Miller & Kingston in 1997.

Don has had excellent results in both criminal law and civil trial practice. In addition, his practice emphasizes credit union law, governmental law, administrative law, civil rights & discrimination cases, business corporations, contracts, construction, litigation, real estate transactions and general civil disputes.

Don represents the Board of Appeals for the City of Cheyenne, Wyoming, and is a contract attorney for the Unified People's Federal Credit Union in Cheyenne, Wyoming in which he assists in litigation, debt collection, U.C.C. issues as well as other general business issues.