There is no single way to write an introduction that will always work for every topic, but the points below can act as a guide.
If you are having trouble putting together a good introduction, start with a placeholder.
That placeholder does not need to be as strong as you would like it to be, but you can always come back to it and edit it.
The introduction also provides relevant background information and puts the study into context, guiding the readers through the rest of the manuscript and helping the authors describe the depth and challenges of the study.
Writing a good introduction can be a tricky task, authors usually prefer to write this part of the manuscript at the end of the drafting process —once they know what the article will contain and how it will be structured— to ensure that they do not miss anything.