The advice I give my students is this:
- Pick a SECTOR or INDUSTRY to work within - something that interests you (healthcare, law, manufacturing, education...)
- Pick a TECHNOLOGY AREA that interests you (front-end app development, computer science, data, networking...)
- Combine the SECTOR/INDUSTRY and the TECHNOLOGY AREA and brainstorm some ideas (e.g. create an app for accessing a patient record; design a new generalisable database for tracking the manufacture of goods; design a proof-of-concept P2P network for off-grid emergency services...)
- For each idea, use Google Scholar, search on the keywords and read about what others have done (abstract & conclusions). Note down any further research questions/future work/areas for improvement).
- From this, you can derive unanswered research questions. Write one or two research questions for each of your ideas.
- Rank your ideas based on how desirable you find them (this is important) and how achievable you think they are (both the problem itself and considering your current skill set), scale of 1-10.
- Your top-ranking idea (add the ranked scores per idea) should emerge as your leading candidate for further investigation.