I have a bound notebook, which I call my ideas book. Whenever I get an idea, I write it on the notebook, one idea per page. The rest of the page goes for detail

I have a bound notebook, which I call my ideas book. Whenever I get an idea, I write it on the notebook, one idea per page. The rest of the page goes for details like features, implementation ideas etc. Whenever I have some time to hack away on personal projects, I just flip through the notebook, choose an idea and go with it.