[1] Born in Ciudad Bolívar, Prieto grew up in Caracas and attended public schools, where he learned and developed his skills as a salesperson to advertise and sell products.

He worked as a promoter for the Cardenales la Guaira BBC and then became part of the leadership of the Sabios de Vargas,[1] clubs that participated in the Liga Nacional de Béisbol, which had stabilized the first national championship of first division in Venezuela since its inauguration in 1930.

[2] Additionally, Prieto broadcast baseball games on radio and worked closely with Pablo Morales, a businessman and baseball team owner, managing operations in regards to team events and planning budgets.

[1] Afterwards, Morales served as president of the International Baseball Federation in a span of four years between 1946 and 1952 and also headed the organizing committee of the VII Amateur Baseball World Series held in Caracas in 1944.

[3] Morales would remain the sole owner of the team until shortly before his death in 1969, when he included Prieto as legal partner.