Communist revolutions have been attempted across the world - what were the primary reasons that the Cuban Revolution succeeded while others failed?
The Cuban revolution succeeded because it was a broad-based revolutionary movement, not a "Communist" revolution (initially, that is). For instance, in the July 26th (1953) uprising against the government's military barracks (the equivalent of John Brown's raid on Harper's Ferry before the U.S. civil war), the Castroites were only one of several revolutionary groups revolting against the unpopular dictator, Batista.
Castro was captured and condemned to 15 years' imprisonment, but was released in 1955 under a general amnesty.
In 1956, the Castro supporters fled to Mexico, where they were joined by other revolutionaries, notably a student group called the Revolutionary Directorate (RD). This group returned in Cuba in 1957, and launched a suicidal attack against Batista, while Castro bided his time and returned later.
By this time, Batista was losing most of his supporters. In 1958, the U.S. recalled its Ambassador and withdrew its diplomatic recognition of Batista, placing a key embargo on military goods. Meanwhile, one of Batista's opponents was an American "soldier of fortune, William Alexander Morgan. When Castro returned, he was joined by Morgan and the surviving RD members. Their combined efforts were enough to bring down Batista.
After the Revolution was successful, Castro's Communists "hijacked" it because they were better armed and organized than the other revolutionaries. But that is another story.
Castro was a communist of convenience. He would have chosen the political system and economic system that would have perpetuated his revolution's, and his, grasp on power during his lifetime and beyond. In this respect the Cuban Revolution was a complete success and it accomplished it's primary goals. To break US dominance.
Castro was a nationalist and anti-imperialist first. He would have chosen to ally himself with the US had it been the most convenient route to accomplish his goal of a Cuban-free of US dominance and the ability to have self-determination. We need to recall the international political atmosphere of the 1950's and US hegemony over Cuba, and Latin America, since Cuba won it's "independence" over Spain. Cuba would have eventually won it's independence from Spain and US intervention stole that victory and symbol of national pride.
Subsequent to "independence, Cuba was occupied by the US and only after agreeing to the Platt Amendment was the US occupation ended but Cuba remained under the US boot. Platt Amendment made Cuba a vassal state to the US and these strings needed to be broken and that process started in 1959 with the Revolution.
The US, as was typical in the region and elsewhere(think Iran, Guatemala, Chile, Vietnam, Panama Canal, etc.), resisted such independence and tried to squelch the breakaway by undermining the Revolution and overthrowing it. Sensing the imminent US intervention drove Castro into the Soviet camp, not out of ideology but what he perceived as an existential threat. It was about survival, not ideology.
Castro was a pragmatist and there were both Marxists and non-Marxist wings in the Revolution, granted that his brother Raul and Ernesto Guevara were Marxists and had Castro's ear but there were also the non-Marxist that also had his ear who feared US intervention and wanted to return to the previous status-quo. Given the US attempts of interference in Cuban affairs and assassination attempts against Castro he concluded that to survive physically and otherwise that he had no other option but to purge the non-Marxist and pro-US elements from the Revolution thus driving the Revolution into the Soviet Camp. So the Raul/Guevara wing won out and the Matos/Cienfuegos wing lost. The rest is history.
Cuba's true date of independence was actually January 1st, 1959.