Join a golf club or use a handicap service that follows the World Handicap System
Post scores from at least 54 holes, such as 18 holes, 9 holes, or a combination
Use adjusted gross scores for each round
Record the course rating and slope rating for each course played
Apply the handicap formula or let the handicap system calculate it automatically
Use your best score differentials from your most recent rounds
Average the selected score differentials
Multiply the average by 0.96 to get your handicap index
Convert your handicap index to a course handicap using the course slope and rating
Update your handicap after each eligible round