Throughout your methodology chapter, and/or in a specific part of it, you should justify (identify the strengths) your methods:
State why you think the methods you are using are the most appropriate for the research question(s)/hypothesis(es).
Discuss not only the benefits of the methods used, but also the disadvantages or limitations, and how you overcame them.
Possibly acknowledge alternative methods that were considered for the research and why these were disregarded.
Include sources and references that support your choice of methods and procedures.
Justification for your research project can stem from your literature review. For example:
Methodologies used in other studies may contradict existing knowledge about the phenomenon, inspiring you to offer a new approach.
The methodology another researcher employed did not adequately explain the phenomenon, leading you to develop a more accurate approach.
The methodology other studies used was problematic in some way and you took the opportunity to rectify the issue.
At some point in your methodology chapter you should mention the delimitation and limitations of your study.
Presenting delimitation and limitations is not a sign of weakness, rather, it's a sign of strength! It's very academic - and wise - to be aware of the limits of our own research, to know that there is only so much we can say with certainty, and to appreciate that our insights may not be applicable and generalisable to other contexts.
Delimitation and limitations can be described as follows:
Delimitation = intentional choice of the researcher as to the boundary of the study - what it incudes and what it excludes. It can relate to population, location, sector, research objective, methods etc.
Limitation = constraints that are outside the control of the researcher and will affect the outcome of the research in terms of generalisability, validity and reliability.
Check out this useful video on setting boundaries and narrowing down the scope of your inquiry.
In the concluding part of your methodology:
Summarise the main factors of your research method and how these will then be employed to the analysis of the results.
Be positive and address why, even with the limitations and weaknesses identified above, you have chosen this research method.
You could recommend how to improve the research method in future, or what could be done in future to further this research.
Offer a transition into the next chapter.
Lastly... find below some tips on the writing style for your methodology:
Write clearly and concisely.
Do not stray into background info, interpretation, or irrelevant detail.
Write from your reader’s perspective. You won’t need to explain things they already know, but you will need to paint a precise picture of your methods.
Whilst not always possible, the methodology should be written in chronological order.
You should use the past tense.
Check with your supervisor if you can use the first person (“I” or “We”). Alternatively, you could state, for example “the researcher provided participants with…”