This can be one of the most difficult tasks for any researcher, to select a topic and then to focus and refine that subject area to produce a viable proposal.
One of the common mistakes is to set targets which are just too ambitious and not achievable in terms of either the extent of the research or in the level of information which the researcher hopes to uncover and analyse.
Most new researchers are surprised by how little scope can be achieved by a research project in order to get enough depth of research and rigour of investigation of the topic. Clear and early restriction of the study will ensure adequate depth.
You should also consider at an early stage the resources available to you.
These include the number of hours you are willing to put aside each day / week / month to do your studies.
Research is not an easy option. Research is hard work but often the most rewarding form of study. The satisfaction and sense of achievement derived from a project completed well can be enormous; the efforts are well worthwhile and provide the researchers with expertise and insights for future work.