The end result is that you should be able to come out with a perfect script. But the best way in doing these is to proofread and edit your work after every major idea. Keep in mind that there must be a link between every point.
At the end of every point that you write or at the close of the whole paper, there is the need to edit what you have written. Always think of the main aim of your essay when you write down any idea. This will be the basis for your editing. Your main aim will be to bring out something to the knowledge of your readers and this will only be by making them understand all what is found in your paper. Your aim will not be fulfilled if the readers do not understand and grasp what is in your essay. Therefore, edit to remove any ambiguity that may prevent the readers from understanding your essay.
Essay proofreading and editing should never be taken as an uncertain pursuit or something that must be done only when you are satisfied that your essay is complete. If you intend to edit and proofread at the end of the writing, you should allocate enough time for doing these. A reasonable student should know that proofreading and editing equally takes time and patience similar to the actual writing. If you can allocate at least a third of your time for these, it will be an excellent pursuit. Once you are through with proofreading and editing, go over it one more time. It is even best to get colleagues or friends go over the work for you.