Thanks Steve for sharing this. I am sorry to hear about your condition. I am sure as you survived Big C, you will survive the small C as well. Take care and thanks.
By "Make decisions easy to change later", do you mean,
1. Getting the Module structure of the system correct with well defined contracts between them so that they can be changed, updated independently of each other.
Do you want to share any further insights about what factors you use to narrow down the choices about the correct ways? Similarly how do you go about managing the Constraints & Trade-offs - Do you change the scope? Do you negotiate to relax the constraints etc.