[fzwang]

I used to work in VC and second this. Nothing really preps you better than the real deal. Line up some practice rounds with low-stakes investors first.

The issue with using founders/friends is that they're too emotionally invested in you to ask the hard questions in ways the investors will. Founders also think differently than investors. For example, a friend who has built companies before would look at a potential issue and their "operator brain" would automatically come up with ideas on how to address it. As a result, they may downplay the problem. Whereas an investor may laser in on it to test your thinking/confidence.

If you had to practice, making the question submission anonymous (as you can) may help. I know I hate giving harsh feedback to friends directly, even if they ask for it. The sting still lingers around. Not knowing who asked the question could be helpful, but it's possible they would still be able to tell if they know you.