Ensure the editor you are contacting accepts email query letters. While it is becoming increasing more popular, some editors still prefer snail mail query letters. Make sure your email will be accepted before you send it. [2] X Research source

If necessary include  to include any attachments.

Use proper grammar. Don’t use net-speak. If you wrote your email in a word-processor and then copy-pasted it to email, check for characters that did not copy properly. Often word-processors use special characters that will appear as gibberish in email programs.