Introduction

 The introduction can be one of the hardest parts of a paper to write, but adopting this approach helps you to focus on how you want to start and what you specifically need to say. Most readers want a quick and snappy introduction to your  work. Topic sentences, especially for the first introductory sentence, are a great help. These sentences are discussed in more detail in Chapter 8. Richard Smith, editor of the BMJ, stresses the importance of trying as hard as you can to hook your readers in the first line.
The introduction is where readers like to find the information that tells them exactly why you did the study. Few readers want to plough through a detailed history of your research area that goes over two or
more pages.  In the introduction section, you do not need to review all of the literature available, although you do need to find it all and read it in the context of writing the entire paper. In appraising the literature, it is important to discard the scientifically weak studies and only draw evidence from the most rigorous, most
relevant, and most valid studies. Ideally, you should have done a thorough literature search before you began the study and have updated it along the way. This will be invaluable in helping you to write a pertinent introduction.