I often share a tip or "hack" at the beginning of class. Some of these I borrow from Robinson's What Smart Students Know and Newport's How to Win at College and How To Become a Straight-A Student. I also recommend the following tips.
Email Subject heading
When you email someone include a subject line. Subjects might seem superfluous if you are used to text messaging, but subject-less emails are more likely to be missed or filtered as spam.
Even if you spoke with the person earlier, provide some context in the email. Some people, especially teachers, interact with dozens if not hundreds of people a day. If you change something, like the time of a meeting, include all the information necessary, not just the "diff."