The abstract is perhaps the most important section of your manuscript for several reasons. First, the abstract is the first section that is read by journal editors when deciding whether to send your manuscript for review. Similarly, once your work is published, it is the first section that is examined by readers; in many cases, it is the only section of the manuscript that they will ever read. This is in part because most literature databases index only abstracts, and access to full-text articles is often restricted.
In order to write a good abstract there are some tips we can follow in order to be successful!
1.- Write a paper first, The manuscript can then be used as a guide to write the abstract, which serves as a concise summary of your research.
2.- Provide introductory background information that leads into a statement of your aim, it can not be longer than three sentences, you need too express your aim clearly.
3.- Briefly describe your methodology, The methods section of your abstract is your chance to summarize the basic design of your study.
4.- Describe the most important findings
5.- State a conclusion
Adapted from: https://www.aje.com/arc/make-great-first-impression-6-tips-writing-strong-abstract/