One of the biggest rookie mistakes that beginning filmmakers make is that they try to stuff everything into their movie and end up with a six hour monster. Problem is, most beginning filmmakers don't have the experience or the skills to pull something like this off and they end up with a muddled disaster.
So, what you want to do, when first starting out, is make the film shorter than you actually want to make it. Leave the audience wanting more...even a sequel. In fact, you might want to leave the ending of the movie open ended so that it lends itself to a sequel. You can never give the audience too little, but you can give them too much.
What you should do is map out your whole movie ahead of time with storyboards.
For example, let's take this murder mystery.
1. Murder is committed.
2. Police arrive on scene.
3. Investigation begins.
4. Suspects are questioned.
5. Clues begin to surface.
6. Hint of who murderer is surfaces.
7. Final clue reveals murderer.
8. Murderer is hunted and caught.
It's basic, but you get the idea. Then, after you have your storyboard designed, you fill in the pieces as sparsely as possible. Don't drag things out. If you find your storyboard is pages long, then your movie is probably way too long to begin with. Storyboards should be relatively short and simple.
Here's a few of his tips to follow.
STEP 1: It's the Mind of the Audience
Hitchcock says that nothing is more important than getting into the mind of the audience. You have to sit down and think how each scene is going to affect the person watching. Will it make them happy, sad, angry, what? This has to be thought out for each scene. You want to make sure that what you write hooks them. There should be no moments where they want to leave the theatre to get a snack. Make them want more with each passing minute.
Hitchcock understood that people went to movies to have fun and that no matter what happened, nothing would actually happen to them. So you could have people falling from planes, cliffs or whatever, and it would be okay. In other words, take them on the wildest roller coaster ride they've ever been on.
STEP 2: Frame for Emotion
Emotion, whether it is fear, laughter, surprise, sadness, anger, boredom, or whatever, is the ultimate goal of each scene. When placing the camera, you want to first decide what emotion you want to invoke as each camera angle will invoke a different one. The closer you are to the character's eyes, the greater the emotion. The farther away, the less the emotion. By changing from a far shot to a close up gives the audience a sudden surprise.
This is how Hitchcock mapped out every scene. if you watch his movies you will see him use changing camera angles within a scene quite often. He says it's the same as composing music. He mixes up the angles he way a composer mixes up his chords and melodies.
STEP 3: Camera is Not a Camera
The way Hitchcock played with the camera was pure genius. He said that the camera should not act like a camera, such as being in one place. It should follow the actors around the room and be like another actor. This makes the audience feel like they are more involved in what's going on.
Hitchcock got this technique from his days in silent movies. Without actors speaking words, he had to rely on camera movement to tell his story. This works just as well with today's movies and it's a technique many movie makers have copied.
Don't try to re-invent the wheel. Follow what other film makers have done and you'll do just fine.