Here are a handful of useful primers from:
1. Chris Blattman (Professor of Political Science and Economics, Yale University)
2. Michael Leddy (Professor of English, Eastern Illinois University)
3. The Wellesley College Social Media Project
The key point of all of these is that an e-mail sent to your professor (advisor, employer, prospective employer, etc.) is a professional communication. You should treat it as such. Be thoughtful, be polite, and be concise.
If nothing else, these are good habits to develop. You will be writing to people to people for help, advice, information, appointments, and jobs, among other things, for the rest of your life. Beginning to develop good habits as a correspondent now will pay dividends for a very long time to come.
