Broadly, research methods are either quantitative or qualitative.
Qualitative Methods: Include focus groups, interviews, case studies, etc. This method is more subjective and uses primarily an inductive process to formulate a theory or hypotheses. Typically provides more in-depth information on a few cases. Response options tend to be either unstructured or semi-structured. Typically does not involve statistical tests. Results are less generalizable. Time expenditure is lighter during planning phase and heavier during analysis phase.
Quantitative Methods: Include surveys, reviews of records for numeric information, etc. This method primarily uses a deductive process to test a hypotheses. Typically provides less in-depth information, but has more breadth across a large number of cases. Response options tend to be fixed. Statistical tests are used for analysis. Results are more generalizable. Time expenditure is heavier during the planning phase and lighter during the analysis phase.
Above is a link to an encyclopedia entry. Very short and briefly covers the topic. A good starting point.
Above is a link to a book that covers qualitative research design & methods. These methods are specifically covered: case study research, ethnographic research, grounded theory research, focus group research, action research, narrative research, discourse analysis, and critical research.
Above is a link to a book that covers mixed methods research. Mixed methods is the process of using both quantitative and qualitative research methods.
Above is a link to a book that explains quantitative research and how to design it. Ignore the SPSS chapters (unless you are using SPSS).
Above is a link to a book that covers quantitative methods. It is a deep dive. This will be of more use if you already have a quantitative method in mind and want to learn more.
Above is a link to a book that covers qualitative methods. It is a deep dive. This will be of more use if you already have a qualitative method in mind and want to learn more.
Video introducing reasoning in qualitative and quantitative research
This video covers qualitative research methods.