Q: What is the best way to write an effective introduction?

Basically, what the reviewer means is that your literature review is not substantial. The purpose of the introduction is to set the context and explain to the readers the significance of the problem at hand, whether any previous work has been done on it or on a closely related topics in the field, what the previous studies have achieved, and how your research aims to address the problem.   

Ensure that your introduction does the following:

• Describes why you have undertaken the study
• Explains how the research will make a significant contribution to the field
• States the research question clearly
• Provides a background of the problem that your research aims to understand or resolve
• Summarizes what is currently known about the topic through existing literature and citing studies that are relevant

To know more about structuring your paper to convey your ideas impactfully, refer to Manuscript structure: How to convey your most important ideas through your paper.