He was a member of the first group of muralists commissioned during Post-Revolutionary Mexico, working alongside José Clemente Orozco, Carlos Merida, and Diego Rivera. From the fecund milieu of 1920s Mexico, Amero fully embraced its lessons and began to express his personal vision in painting, printmaking, illustration, photography, and filmmaking. In particular, Amero developed a great passion for lithography, establishing several print workshops during his career and would influence a generation of young artists.
Like many of Mexico's leading artists of the day, Amero had an important relationship with the United States. In the late 20s, he went to New York City via Cuba, where he worked as an illustrator for several publications and Saks Fifth Avenue. More important was the lithography lessons he received from George Miller, the master lithographer.
He returned to Mexico in 1930, where he established with success a lithography workshop at ENBA. Among the artists who attended by such noteworthy artists as Bracho, Jean Charlot, Olga Costa, Gabriel Fernandez Ledesma, Francisco Diaz de Leon, Dosamantes, Carlos Merida, Chavez Morado, Orozco Romero, and Alfredo Zalce.
A few years later he returned to New York, where he became a teacher at the Florence Cane School of Art, a commissioned Works Progress Administration muralist, and experimental photographer and cinematographer. He developed a friendship with the poet Federico García Lorca who wrote a script for a Dada-esque Amero film involving anthropomorphic machines. He also had his first solo show at the Julian Levy Gallery and subsequently helped Henri Cartier-Bresson exhibit there.
In the 1940, Amero went to Seattle to teach at the Cornish School, which had attracted such innovators as Martha Graham, and John Cage. In 1946, Amero took a professorship at the University of Oklahoma. There, he established a world-class print workshop which he led until his retirement in 1968.