Decide the information to present
One of the biggest problems when writing is not what to say but what to omit. Many scientists are in favor of the “deck method”: all the data is collected and shuffled on the screen until they are shaped into an article.
To write a research paper with quality there is another method, which is to write the article message (third step) in the center of a large sheet of paper. This message is surrounded by the questions and answers necessary to support it. This process is known as the "mental plane technique". It is very useful to choose what has to be said and what can be omitted.
Set the Manuscript Structure
Writing is a linear activity. Therefore, it is necessary to set a certain structure for the manuscript. First, you should consult the magazine in which you want to publish and analyze the structure of existing articles. You have to pay particular attention to the different sections. In the original articles, there will generally be four: Introduction, Methods, Results, and Discussion. It is convenient to observe how many paragraphs each section has approximately (a usual structure is two paragraphs in the introduction, seven in Methods, seven in Results and six in Discussion.
To write perfectly I should check whether key phrases appear (eg at the end of the Introduction and the beginning of the Discussion). The first sentence of the Introduction is usually a "minicompound" of everything we already know and is generally boring and formulaic. More important is the last sentence of the introduction and the first sentence of the Discussion. The last sentence of the Discussion should be a clear exposition of the article's message.
Many people spend too much time at this stage, mainly because they are not only writing, but also structuring and revising at the same time. If the structure of the article has been previously established as we have suggested in the previous step you can write very quickly: An Introduction can take no more than 10 minutes, for example.
The important thing in this phase is not to waste time worrying about the details, and to obtain on paper a clear and coherent first draft. At this stage it is very useful to follow the advice of the American writer James Thurber: "don't write it well, just write it.