Great list:

• Spend 95% of your time researching the person you’re emailing, and 5% writing the email.
• Introduce yourself quickly but specifically, and ask specific questions.
• Ask one or two questions. Not three! You’ll feel like adding a third because your email looks too short. It’s not.
• Google your questions first.
• Don’t offer to “hop on the phone” as a compromise. That’s not a compromise, it’s a threat.
  
• Say “Even one sentence would be great.”
• Novelist Tao Lin came up with this one: Tell the recipient it’s OK to ignore your email. Not just to say no, but to completely ignore it.
• Say thank you.
• As soon as you’re ready to send, find and delete at least one sentence.
• Send and move on. Never “follow up.”