Many have tried, but few major summer releases have achieved the kind of success that “Pirates of the Caribbean” and “Transformers” have enjoyed. Critics panned the last installments of both of those films, but audiences will still turn up in droves on opening weekend for their sequels. It’s no accident that “Pirates” is the only major film being released this Friday. Savvy studios know it will trounce any competition.

So what was it about “Pirates,” “Transformers” or “Iron Man” that made them so successful? A few experts explained to us the “must-haves” for a blockbuster kingpin.

1 Early awareness: Ever see a trailer for a film that’s not coming out for another year? Frustrating, yes, but it’s a very specific tactic that’s meant to build up anticipation and get people talking.

“The point is to create engagement, so that people have experienced the movie already and they want to know the whole story now,” says Grant Powell, CEO of digital branding creative agency Pomegranate.

Grae Drake, co-critic at, has seen this early-trailer effect at work.

“They plant it into our consciousness even a year before it’s released, so really we’re being trained to anticipate them,” she explains.

2 New special effects: This law goes back to the “Star Wars” era, but was more recently proved with the success of “Avatar,” the most expensive movie of all time. “People love special effects. It makes the movie seem like more of a movie,” says Paul Levinson, professor of media studies at Fordham University. “These kinds of things are easy to understand and you can explain by word of mouth a great special effect more than you can a complex plot.”

3 A strong leading character: Jack Sparrow, Tony Stark, James Bond — what do they all have in common? Charisma makes them endlessly watchable.

“The biggest part of it is that they have created a character [in Jack Sparrow] that speaks to everyone,” says Drake. “You’ve got people on dates. You’ve got old married couples, children. Everyone likes Jack Sparrow just like how everybody likes big shiny robots smashing things.”

4 Peer pressure: How did Hitler get an entire nation to go along with his evil ideas? The Institute for Propaganda Analysis studied his tactics in the 1940s. Their answer, creepily, also explains why we have “must-see” movies today. It’s a social theory called “the bandwagon effect,” as professor Levinson explains.

“Some significant number of important people in your life are talking about a movie saying, ‘This is really good, you have to see it,’” he says. “Everybody has a point where a switch is flipped and suddenly you feel like you have to see this movie. That’s because of this very deep-seated feeling that we like being with a crowd of people headed in a certain direction.”

For more movie news follow Heidi Patalano on Twitter @HeidiatMetro.