Abstract for a thesis or research paper as said should make your readers have full understanding of what your work entails. An abstract which is not effective will usually be vague and will not give out complete information of the paper or thesis. This article will tell exactly how an effective abstract is usually written:
1- Identify key areas of your paper: Abstract is brief but still a comprehensive write-up that in few lines explains everything that is there to know in the paper. Since the abstract‘s job is to cover a broad target audience and then based on interest audience decide whether they want to proceed reading or not, it is important that it features all key areas of your work which will help the audience make this decision with ease.
2- Abstract should cover your research problem: Always make your abstract research problem centric, use your research problem as the center around which your abstract will revolve, highlighting different aspects.
3-Methodical approach: Your abstract should highlight how you have approached the paper, how you have worked on to resolve your research question and how it adds an overall value to the underlying problem that you found out through your research.
4- A proper conclusion: If an abstract is a short write-up, it does not mean that it will not require a proper conclusion; abstract also should be provided with an effective closure. It is the part of your research paper which will serve as the first impression among your readers so everything has to be perfect.
The final thing to note down here is that often people use the word abstract alternatively to a summary, it is important to understand that summary is a completely different concept than an abstract and both have different criterion.Resource: http://goo.gl/meIsGh