Recommended Todo list:
1) Read how to prepare according to YC
2) Make an exhaustive list of questions you can get
- Usual questions: you'll find a good list here + all the questions from the application form
- Think about questions specific to your business you might get (eg how do you compare to that competitor, how does that specific feature work, etc)
- Good video from Garry Tan
3) Build a table with all the questions and for each question
- Short answer (20 seconds)
- More info to have in mind if the interviewer decides to dig more
- The cofounder who answers
- Below an example of one of our questions:

4) Figure out what is your superpower (could be your product, your traction, your team, a unique expertise, etc) and make sure you pass that message along during the interview
- For us, it was our product. We made sure to show it because we knew that was the most impressive thing about our overall application.
5) Practice, practice, practice
- Use this awesome tool and / or this brand new one built by an W20 company.
- Do 2 or 3 mockup interviews with YC alumni, maybe you know a few, many also offer on twitter to help. I'm also happy to help. Hit me up on Twitter
6) Go to the interview and kill it
Final word: the best thing you can do before you interview is grow. If you have 0 users, try to get 1, or 2. If you don't have a product, try to get a minimal version by then, etc.