Most people don't know that a movie trailer, which previews an upcoming film, has the name because when they were first introduced in the 1940's they were at the end of movies, therefore 'trailed' the feature people just saw.
Now a days movie trailers are an industry onto themselves. With post houses dedicated to only produce the best cutting edge movie ad experience ever.
But what makes a good trailer? And what are the specified hooks that can get a viewer interested in watching the movie or more likely pay for a ticket? The answer is not that simple because what is great to somebody is O.K. to another. But the science of trailer making (after many years or experimenting) has been boiled down to a small formula : 1) Opening 2)Main theme 2) Action and 4) End Piece.
As a example we'll use the new GUARDIANS OF THE GALAXY Vol. 2 movie trailer.
Movie goers today are very sophisticated and have almost an uncanny knowledge of stories, so how can you hook their attention? With the first part of the formula - Opening. And what do you use? Images... Stunning images or interesting ones. Sometimes you don't need fast images or orchestrated explosions but something that catches the eye. Open the trailer with something creates a question, a choice or reaction. In the Guardians trailer they show great openings, a cool Space Station, Starlord facing overwhelming odds and Drax jumping into the jaws of a menacing space creature... Got your attention? It sure did.
Then you must follow with the Main Theme. So is this movie an action, sci-fi or drama? The following next images in the middle of the trailer must show what tone the movie has but also, if possible, what is the story about. How it will create the question : is this something I want to watch? It must make you take a decision right away, to buy or not. In the Guardians trailer it uses very cute but straight forward comedic situation. Rocket explains a life and death situation to Baby Groot - who get's the order totally wrong - two times! This creates the perfect tone for understanding the movie. Is it comedy? Hell yes. Now the Guardians trailer is very light on story content, mainly because it's more of a 'teaser trailer' but also people are familiar with the characters and the fans will want to follow them no matter the adventure.
Now having the opening and tone set, you must sell, sell, sell... And how better than to show what you got. After tone is set you then add the best most interesting visuals you have. Crazy shots, fun shots, slow motion shots... And of course music is crucial. Having money for recognizable hits like the studios have helps, but you can get many royalty free music to use in your trailer, but make sure the rhythm is in tune with the image beats and tone. No Heavy Metal on a drama trailer, but you get my point. In the Guardians trailer you see interesting images, that convey action, skill and coolness. All factors that sell. Placing them to a catchy '70's pop song just heightens the fun.
After now establishing all these pieces you go back to one last scene to nail the tone. This is many times call the 'end piece' but not all trailers have them or specifically need one. But if you got enough scenes that work it certainly doesn't hurt. The Guardian's equivalent is the last scene with the mind reader. Cleverly edited to where you have blatant over reaction by Drax which works because it's so over the top it makes you laugh.
So there you have it folks. The basics on making an engaging trailer. Remember like most things practice makes perfect and don't expect good results in your first 3 tries. But again thats the fun in filmmaking. Learning while you work.