Writing an abstract
Abstracts provide the main summary of your work and outside of the title are the part of your manuscript that get the most attention
A guide to abstract writing
Each journal has its own conditions and limits on lengths so this is general
Begin with 1-2 sentences that provide a basic introduction of the larger problem
Next 1-3 sentences of more detailed background specific to your study
Then 1 "However" sentence that sets up the unknown you are addressing
The "however" sentence is followed by 1 main result summary "Here we show" or other type of sentence. For some journals it can also be a here we use this method with this data to do XYZ type of sentence. The key takeaway is that you address the previous sentence
At this point add 2-3 sentences summarizing the results of the study
Conclude with 1-2 sentences of broader perspective (zooming out) to highlight the big picture implications of your work
To the extent possible, try to limit yourselt to 200 words max. The more you write the less abstract it becomes
The special case of the nature summary paragraph
Nature uses a opening paragraph that follows a similar formula but is slightly more nuanced. Luckily there is a guide on how to write this style of summary paragraph that is well worth looking at even if you are not in the process of writing a nature paper!