Mistakes are Useful..

..only if you learn from them.

And you can learn from them, only after you have admitted that you have committed one.

Blaming others (people, circumstances etc) for your mistakes means you are distancing yourself from the possible learning that might come your way.

If you have not committed mistakes in your life, you clearly lack experience.

IMHO, learning from your own mistakes requires few qualities.
Most important of them being, being able to role-play yourself in situations where you made mistakes. i.e able to go beyond denial mode.
Second, self-confidence that is needed to admit things.
Third, courage which is needed to bring changes.

So, In short:
1. Admit your mistakes. Be wise.
2. Make sure to make use of your mistakes. Learn from them.
3. & MOVE ON to next venture.

Remember: Mistakes are not shameful things.

What have I learned...

- Always plan assuming that it would change sometime soon. Still plan.
- Understand risk management. Many people claim to understand risk, but that is not true.
- Identify your blind spots (thought process). This will take years and a mentor to do it right.
- Hope for the best. At the same time be prepared for the worst. This is not easy to do both of these at the same time.
- Learn to learn from what people *did*, not what from they *think*. (Even if they have failed.)
-- Opinions are just opinions.
-- Strategy is also just a strategy until it's executed (even if you fail).
- Execute quickly...and if you have to, *fail early*. Or *Pivot* into new strategy before you start hearing about it from outside.
- Don't paint everyone with the same brush. Context/perspective is the key to understand the world around you.