Christian's Sales Hack: Keep it short, concise, and to the point
A tip I always remember from my first day in sales -- 'Keep it short, concise and to the point.'
For context, when writing an email; Applying this hack is to limit every email to 3 lines or less. Be very clear on the purpose of your mail (information sharing, asking for advice, doing a concrete proposal) and limit yourself to 3 lines maximum. End your emails explaining in one sentence in your signature why you keep your mails so short.
This simple method will force yourself to think about the purpose of the mail, and to be short and concise. The people you communicate with will benefit, and will hopefully return the favors.