Job interviews, consulting cold emails, VC, someone who has the keys to your destiny and does not know it yet.
The most important things are, in my mind:
1. If possible, make the email actionable for the other party.
2. Don't waste the other party's time.
3. The more you write, the more opportunity you can shoot yourself in the foot. Remove sentences you don't need.
This has been my ticket to opening new doors so many times. Make it easy for people to help you.