He had a short career as footballer, playing only in the 1976–77 season for Pro Sesto and in that 1978–79 for Rovellasca in Serie D. In 1982, aged 23, he became a coach for amateur team Abbiategrasso's youth squad, and 1984 for Monza's.
This was confirmed by the club a few days later; he left Siena after a very impressive season ended with a record 44 points, the best result in Robur's time in the Italian top flight.
However, on 22 July 2010, just a month after his appointment at the helm of the squad, Paok chairman Thodoris Zagorakis decided to sack him due to poor pre-season results and rumoured complaints from some players.
[8] On 6 December 2010, Beretta was announced as new head coach of Serie A relegation-threatened Lombardians Brescia, replacing Giuseppe Iachini at the helm of the Rondinelle.
After Siena, he agreed upon a contract with Latina of Serie B in July 2014, only to mutually end his deal just in October due to what the club considered poor results (seven pts in seven matches).