Tips on Writing a High-Quality Abstract
NCBI/NIH Guide to Writing a Scientific Abstract: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732725/
The key goal of an abstract is to clearly and succinctly describe the relevance, details, and excitement of your research project. The abstract should be interesting and informative and should also be easily understood by scientists who are not familiar with your area of study. It is preferable to use simple declarative sentences and to avoid the use of the passive voice. It also helps to avoid, or minimize, the use of abbreviations and acronyms. Where abbreviations and acronyms are essential, they should be spelled out on the first instance. Plan on your abstract being approximately 2500 characters in length. It should begin with the list of author names and institutions, then conclude with an acknowledgement of the funding source(s) that supported the work.
The basic elements of an abstract are the title, hypothesis, methods, results, and conclusions. The title should be brief, but clearly convey the central message of the study. In fact, it should be possible to understand the entire point of the study from the title alone. The hypothesis, or aim of the study, should be stated in the first two or three sentences of the abstract and be presented in the context of critical background information (i.e., studies or data that inspired the current hypothesis). This should be followed by brief and basic information on the experimental approach and the types of measurements that were made. In the case of clinical studies, it is a good idea to state whether the study was retrospective or prospective, and whether there was randomization. The results (they can be preliminary) should be summarized clearly and avoid the inclusion of detailed data sets or lists of numbers. The results should also be presented with the hypothesis in mind to make it easy for the reader to understand how the data impact the hypothesis (i.e., avoid presenting data that don't specifically address the hypothesis). Finally, there should be a clear interpretation of the data as they relate to the original hypothesis and perhaps a statement on the significance of the resulting scientific advance. A statement on possible future directions can also be included, if appropriate.
It is a good idea to have a colleague review your work to spot mistakes and to check for syntax and sense. Remember, a well-written abstract will convey key information to scientists within the field, yet be readily understood by scientists in other areas. Aesthetics matter as well; make it easier on your reader by dividing the abstract into a few paragraphs. And nothing mars an otherwise excellent abstract more than careless typing or proofreading, so be sure to spell-check for typos and ensure you have employed consistent formatting throughout.