If you are writing a dissertation or thesis in an educational institution, there is very likely to be guidance specific to your institution or department, including expectations and practice. This should be your most indispensable source.

For a very accessible, quick-reference guide to the research process, see:
Thomas, G. (2017) Doing Research, 2nd edn. London: Palgrave.

For a more in-depth discussion of the research process in political science, see:
Toshkov, D. (2016) Research Design in Political Science. London: Palgrave.

For a good discussion of research questions, hypotheses and the application of theory, see Part 2 (‘How to do research: an overview’) in:
Halperin, S. and Heath, O. (2017) Political Research: Methods and Practical Skills, 2nd edn. Oxford: Oxford University Press.

For more in-depth discussions of the process of an undergraduate dissertation or research projects:
Greetham, B. (2014) How to Write Your Undergraduate Dissertation, 3rd edn. London: Macmillan.
Thomas, G. (2017) How to Do Your Research Project: A Guide for Students, 3rd edn. London: Sage.
Walliman, N. (2014) Your Undergraduate Dissertation: The Essential Guide for Success, 2nd edn. London: Sage.
Whisker, G. (2014) Dissertations and Project Reports: A Step by Step Guide. London: Palgrave.
Whisker, G. (2019) The Undergraduate Research Handbook, 2nd edn. London: Macmillan.