Many people have an idea for a film, yet very few will actually get around to making something of it. Whether it is a lack of confidence or they have no idea how screenwriting works, most people will never try writing a screenplay
For those that will try, simply having this inner drive is not enough. You must combine this enthusiasm with detailed knowledge of how to write a strong, saleable script.
One of the most important things when screenwriting is the strength of the characters you have created. Whether they love or loathe your creations, your audience needs to feel some form of connection to them.
Also, there should be something at stake in the story. When screenwriting, you should ensure that you generate an element of escalating suspense that keeps people interested.
Those who know how to write a script also typically introduce a level of conflict (both internal and external) or obstacles that the protagonists have to overcome. This provides the audience with their much needed sense of drama.
It also helps to write about a field you have experience in, whether as a theme, event or setting, as your understanding of the topic will shine through. However, if you are determined to cover an area that you have little or no direct experience in, you will need to undertake sufficient research.
By investing plenty of time in this before settling down in front of your keyboard, you will reap the rewards in the end.