Nicknamed El Tuco, Alfaro started his career at Platense and, later, joined Salvadoran giants FAS in 1983.
With FAS he won a league title in 1984. He finished his career with Cojutepeque, with whom he lost the 1988/89 national league final to Luis Ángel Firpo.
He made his debut for El Salvador in 1979, and has earned over 15 caps.
He has represented his country in 10 FIFA World Cup qualification matches and, played in the 1982 FIFA World Cup final group stage match against Argentina.
His first job was at Platense, where he was dismissed in January 2005.
He has coached varies clubs in the lower leagues of El Salvador, such as Telecom, Coca Cola, Municipal and San Rafael F.C..
He was coached of El Salvador U-21 and El Salvador U-20, who he helped qualify for the 2010 Central American and Caribbean Games in Mayagüez, Puerto Rico and the 2013 FIFA U-20 World Cup.
He helped to El Salvador U-20 become the first Salvadoran team to win a game at a FIFA U-20 World Cup, by defeating the Australia team 2-1.
Later, he coached in the Primera División de El Salvador for the first time in 2016, leading the recently promoted Municipal Limeño in the Apertura 2016 campaign.
He later resigned, which came as a shock as he amassed a respectable five wins and six draws from seventeen games, he cited crowd problems and clashes with several players, as the main reasons.Salvadoran Premier League: 1