One variation of the technique is to put sub concepts as a network of bubbles connected with lines. The keywords are placed inside the bubbles rather than on the lines.
You can enhance the visual power of your mind maps by putting images near some of the concepts. You can also benefit from using colors for better grouping of the related sub concepts.
In contrast to a linear list of text, a graphic concept map clearly represents relative importance of different sub concepts (by how far they are from the center) as well as how much they are related to each other (by their proximity on paper). Mind map is also easier to extend than a continuous text. When you need to add a new concept, just find some space to branch out a new line.
While such visual exercise can be done on paper, there are also a few graphic mind mapping software tools that could streamline the process. Mind mapping software programs greatly simplify visual map creation as well as management, especially when you need to modify, store, and organize your mind maps on a regular basis.