It’s important to be able to write a good abstract. How else are you going to convince people to accept your journal articles or conference presentations?
Abstracts share a lot with introductions. In both you’ll have to provide context, establish a problem or niche, and then fill in the knowledge gap with your own position. And they both function to get the reader interested in finding out what you have to say.
But you’ll have to go a step further with abstracts. Despite their brevity, abstracts must also contain a brief but concrete presentation of your arguments along with a sample of your data. If you’ve done experiments, they should be described along with the results. While introductions are promises of what’s to come, abstracts have to get the building blocks out in full view.
It’s particularly essential to strike the right tone. Abstracts should be confident without being dismissive of others. Don’t apologise for your work, but don’t overinflate it either. Of course, that applies to any writing, but the whole purpose of an abstract is to help people to decide whether or not to spend time with you and your ideas. Haughty arrogance and abject humility both come off badly.
The Linguistic Society of America has provided a collection of eight annotated model abstracts to get you going in the right direction. They’ve also given a desecrated version of Pullum and Zwicky’s model abstract that is well worth a read. They’ve really done a hatchet job on it — the result is a parody of all the worst submissions. But the pitfalls are ones that people really do fall into. You always need to be on the guard for even a hint of empty overpromising rhetoric. After reading the degraded version, go back to the original (#2) to see how much better it is.