Here are a couple brief email tips that are top of mind:
Set Recipients Last! When writing a long email message, leave the To (Recipients) field BLANK until last, so that if you inadvertently hit Send before the message is actually finished and ready to go, it won't go anywhere!
Attach Attachments First! As soon as you type the words “see attachment” or “please find attached” into the message body, stop typing, and add the actual attachment to the email! If you assume you’ll remember to add the attachment after you’ve finished typing up the message body, sometimes you won’t remember!