Mindmaps are generally good starting points for a new project. You start with the main topic in the middle, just a word or expression. Then you add related sub-topics, connecting topic and sub-topic with a line. Then you add related sub-sub-topics to the sub-topics… you get the idea.
I started like this as well, using the service mindmup.com. It was a good exercise as a starting point, allowing me to map out elements I need to research, questions I need to ask in interviews, etc. But as you should, I have deviated from it somewhat already. I iterated on the structure, added a few things, and decided to drop some others. After a while I did not update the mindmap, as I saw it as a preparatory exercise only.
Nevertheless, if you are interested, feel free to review below (I will try to add an online version, but the share function of mindmup is not playing ball right now…).