I read this article over at Matt Cutts: Rules of thumb.
As soon as you type “I’m cc’ing (someone)” in an email, go up and cc them right then. You look silly when you say you’re cc’ing someone and then you don’t.
This also applies to attachments, nothing worse than saying you’ve attached something, to later receive a reply saying that no file was attached and to resend the email with the file attached.
Another one that I’d add to the list which can apply to a lot of things would be, make a list and check it twice. Check things a few times over always helps to iron out any creases.
