First of all, you will have to decide what type of trailer you want to make. Though, it completely depends on the nature of your movie but still you can play with the visuals and leave your viewers wanting more.
Now, when you are certain about the creative approach to the trailer, work on the storyboard. Making a trailer does not mean that you just take some clips from the movie, place them in timeline and burn the data on CD. You will have to make a complete film of 60 to 90 seconds so you should decide which clip to use in the trailer and why.
Before starting the process, you should watch a couple of movie trailers as this will really help you to understand the basic requirements of a teaser. Sometimes, big budget movies launch a series of trailers which is really effective technique to heighten curiosity. However, it does not mean that each clip is linked to the other rather every trailer is a complete and independent chunk.
Place your selected clips on video timeline and start editing. You must keep in mind that the timing of the clips is complimenting the back ground music. Place your clips according to the storyboard, make transitions, add special effects and then watch them as a final product.
You should watch your trailer without special effects and the transitions. This will give you a clear idea whether the sequence of clips is making any sense or not.
While editing, make it as sharp as you can. You do not want to lose viewer’s attention so there should an interesting clip one after other.
Watch it with some friends who have experience of this field. Do final editing and then export the video.
Contact local cinemas and theatres to run your movie trailer. Similarly, you should also use video sharing websites for the publicity.