Know your audience
In face-to-face conversations, we instinctively adjust our language when speaking to different people. For example, we do not talk to our best friend in the same way as we talk to our grandmother.
However, I’ve noticed that people tend to neglect such adjustments when employing written communication. This is often a major oversight, especially in my area of expertise (graduate applications).
For example, a little known fact is that the people who read graduate business school applications are not professors. Instead, they’re admissions officers who often don’t have a business-related degree of any kind. How might you modify your CV or write your application essays if you were aware of this?
To give an analogy, how might you change your job application strategy if you discovered that your target company’s HR made all hiring decisions? No business managers or directors will read your CV, and no business managers or directors will interview you. Everything will be decided by HR employees who have no operations experience, who come from academic backgrounds unrelated to the company’s industry.
There’s no standard answer to the above, but it illustrates a critical point - for important communications, find out as much as you can about your audience before writing to them.
On a related note, as a professional who crafts and edits written communications for a living, I'll end this (relatively short) post by sharing two pieces of advice:
Employ extra politeness
People often confuse formality with politeness. You can be too formal, but you can never be too polite - as long as you maintain sincerity. This is especially true in an online context, where written sentences could be misinterpreted without the body language and facial expression cues to support the intended meaning.
Let’s say that you received a document that you need for your work from a colleague in another department. How would you respond?
A) Thx ;)
B) Thanks.
C) Got it, thanks.
D) Well received, many thanks!
E) This is fantastic, thank you so much for your hard work!!!
I’d pick D every time. It’s the most polite version that doesn’t go entirely overboard in a way that could be interpreted as sarcasm (see E).
It’s like always saying your “Please’s” and “Thank you’s” - such gestures are the social drops of honey that make others feel better without any cost to you.
Lead with the most important statement
If we were to take a long written email and rank how much time readers spend on each sentence, the first sentence would come out ahead by far, followed by the last sentence, and then everything else.
People tend to carefully read at least the first sentence of a message they receive, but not much else. Therefore, avoid burying your key request in the middle of an email - recipients are likely to forget it or skip over it entirely.
Let's say you're reaching out to schedule a coffee chat. Place this request at the very beginning of your email - or better yet, put it in the email subject.
A corollary to the above principle is that longer messages are often less effective than shorter ones. Don't fit too many ideas into one message, because secondary and tertiary ideas may not be remembered or even read.
If you must include a lot of information, think carefully about the format and the structure. A common example is the CV. When drafting your CV, use bold or italics formatting on the information that you want readers to remember. And just as important, don't bold/italicize too many things (or the wrong things).