What does your planning stage look like? Do you like flowcharts, or lists with features and other things you want to include? Also, how do you organize project related notes that you want to remember for later?
I just use a list of ideas that I have come up with and then a list next to it with things that I definately want to be in my next project. Most of the ideas are brainstormed in the shower
I think mindmap is a good choice. It helps you create many creative ideas. In addition, you can search GG for some ways of project management, I surely works with your situation.