It is a very tough process to choose a topic to research that will be both valuable to the community and interesting to the author. One can advise to just start researching what you like and then see what will be the outcome - the famous principle of YOLO. Although one can choose to do researching this way, without a clear plan and map, it can be very hard to understand what is the scope and focus of the research, and in which direction they are going to. To give a little bit spoiler of the whole process of finding a research topic, the most important thing is having a definite goal and knowing that this goal is achievable.
To help a researcher with the choice of correct topic, there exist a technique that will tell in short time whether the research is worth of starting it. There are 8 questions to be answered that will help to define if the idea is doable, manageable and worthy.
The first question is "What are you trying to do?". This question needs to be answered without any jargons or scientific terms, and explain simply what is the thing that one tries to do or achieve. This could be any goal like making delicious dinner or buying the best computer.
The second question is "How is it done today?". Here it is implied that one should research how others have done it, in order to have an understanding about the topic. The question also covers limits, challenges or any difficulties of the current practice. For the topic of making delicious dinner, one challenge would be that the term "delicious" is a relative one, and the concept of a tasty meal changes based on the geography, culture and individual experiences.
The third question is stated as "What’s new in your approach?". One needs to think what difference they are making with the research. For the previous example of making delicious dinner, one can say that the meal will be prepared using only vegetables growing in a particular area. Moreover, a reason of starting the research could give a hint in answering this question since it could be specific case that will bring novelty. The author should also focus on the reason why he/she thinks that the new approach will be successful.
The fourth question is very simple: "Who cares?". To put it differently, who will benefit from this research and the author's results. For our example, it could be a family who will eat the dinner at the end of the day. It seems pretty simple and obvious question, however, thinking about an exact target group helps a lot in defining the scope and adjusting the topic to fit the need.
The fifth question is "What are the risks?". One should always take into account risks that would lead to the failure of the project. All the scenarios need to be considered because without considering them, the plan of conducting the research will be incomplete and prone to a failure. Like Dr. Strange in the movie of "The Avengers", the author should see all the possibilities of what could happen in the future. This will help one to prevent or mitigate the problems. For our example, it could be not holding enough knowledge about cooking temperatures of certain vegetables and making them either uncooked or overcooked. Also, there is always a slight chance of overcooking a meal (saying from my own experience).
The sixth question is "How much will it cost?". Here, the cost could be of any kind like financial or temporal. Knowing the cost beforehand could help to eliminate the ideas that will take more time or any other resources than available.
The seventh question is put as "What are the midterm and final exams to check for success?" by our professor. This simply says when are the milestones that are most important that need some checking or validation. In our example, midterm could be when a mother-in-law will just come to the kitchen to see how everything is going, and the final would be putting a meal on the table to be tasted by the whole family.
The last but not the least, question of "Why now?" should be answered. It is the one thing that has affected the author's decision the most to conduct the research now. Or the question can also be put that what has changed from the past to today that there is a possibility to do it now. In our example, it could be that the family has moved to that specific area where those vegetables are cultivated.
All in all, these questions are simple at the first sight, however, missing to answer one of these questions lead to some gap or hole within the topic which further cause getting out of scope or time, or maybe the research being completely valueless. Putting these questions in a check-list could really help to define the idea and extract all the "sauce" from it.