To know about the style of writing in an introduction read Writing Styles in a Research Paper.
The introduction section should not take a large proportion of your research paper as you have to provide further details in the next sections.
A good research paper introduces the research problem and provide answers to some basic questions as mentioned above.
The answers to these questions should be presented in a sequential, logical, smooth, precise, and concise manner.
Good hypothesis and objectives are the key to success in a research.
The hypothesis as well as objectives should be constructed with care.
There might be some knowledge gap and you want to find the clues to fix it.
After you are done with the basic background of your topic and its significance now present your hypothesis.
Provide concise but well researched details about the previous researches on this topic and how they related to your topic.
Do not go into unnecessary details you might have to write a literature review where you can provide more details.