A good start is to find a valuable research question
The research question is a scientific question, including two features.
A) There is still no answer to that question. It entails two conditions:
1) This question has not been raised.
2) This question has been answered in a different way that is still challenging.
B) The questions before this question were answered.
Each scientific question requires some prior assumptions answered in the previous studies; otherwise, the research will not have a scientific basis.
Another issue to consider is that when the researcher chooses a subject for a master’s thesis it should be based on some criteria, such as the need of the community, availability of theoretical and practical research facilities, knowledge and interest in the field, career prospects, etc. Choose the thesis topic and try not to change the subject in different stages.
Check the research history. See whether someone else has already investigated the field or not?