A concept map makes clear the relationships between concepts, and helps you to figure out what aspect of a topic is of most interest to you as well as most workable as a research question. You can create a concept map either using software, and some options are below, or with pen and paper. Both have good points and bad points; pen and paper is unmediated, and lets your mind work unimpeded by the time and thought that must go into the hand-to-mouse-to-drawing-tool-to-circle part of working on a computer. However, a digital concept map can be expanded, copied, and amended, allowing for revision of the original in a way that a drawn map does not. You will figure out which way works best for you.
The map structure also works for other purposes, such as:
Digital concept map software: