2 Use a proper salutation: Although you can start an email, send it to a friend. "Hey" is not a problem at all. The best way to avoid writing that the person you contact business. Meanwhile, if you start formal "Dear Sir" is considered outdated. Salutation right you should use is "Dear Mr. / Ms." with the last name of the person you are dealing. If you ever contact or associate with that person, you can still use his first name was (like "Dear John").