First find what methodology you intend to use.

Follow this link

https://www.bcps.org/offices/lis/researchcourse/key_elements.html

regards

In addition to the methodology (which actually sets the rationale for your study) as Laverne rightly pointed out, you'll need to think about the specifics of the research methods and most importantly, not ignoring ethical issues in the retrieval of information from research participants.

According to Sekaran (2003) a research design is set up to decide on, among other issues, how to collect further data, analyze and interpret them, and finally, to provide an answer to the problem.

Sekaran (2003) has identified six elements of research design. They are listed below.

1. Purpose of the study

2. Type of investigation

3. Extent of researcher interference

4. Study setting

5. Unit of analysis

6. The time horizon

Sekaran (2003) wrote:

“The researcher would determine the appropriate decisions to be made in the study design based on the problem definition, the research objectives, the extent of rigor desired, and cost considerations. Sometimes, because of the time and costs involved, a researcher might be constrained to settle for less than the ideal research design. For instance, the researcher might have to conduct a cross-sectional instead of a longitudinal study, do a field study rather than an experimental design, choose a smaller rather than a larger sample size, and so on, thus sub-optimizing the research design decisions and settling for a lower level of scientific rigor because of resource constraints."

For more details please read Sekaran's book.

Reference

Sekaran, U., 2003. Research methods for business: A skill building approach. John Wiley & Sons.