One of my favorite slides is 'Key Lessons', from which I quote:
- "Avoid the temptation to try and build optimal features through extensive planning without early testing of ideas"
- "Experiment often"
- "Try radical ideas. You may be surprised"
The entire presentation is highly recommended. You can tell that this wisdom was earned in the school of hard knocks, which is the best school there is in my experience, at least for software engineering.