Double negatives
Avoid using expressions like not unlike or it is not unreasonable to think… . Your readers have to mentally cancel them out to find the meaning. Remember those multiple choice questions with double negatives? Confusing, weren’t they. Fortunately, expressions like these are not as popular in writing today as they were for the Victorians.

Tone Keep your tone as friendly as you can, given the purpose of the document. Too often we succumb to unnecessary formality in an effort to seem businesslike. But there is nothing unbusinesslike in using a friendly tone. One way to do this is to address the reader. Call this person you. Call yourself I or we. So, don’t say The company wishes to inform… or The bill is now due. Say We at Pringle’s Woolly Underwear wish to tell you… and You can pay this bill at… .

On the other hand, if you are giving a command, don’t mess around trying to make it sound as if you aren’t. Saying something like We recommend you pay this bill by the end of the month is not as clear as saying Please pay by the end of the month.

Gender
Avoid using gendered language. It is no longer acceptable, and using it will definitely distract most readers from the text.

This advice causes problems, however, when we try to use the third person singular pronoun he or she. Are we going to write both of these pronouns every time we need to use one or the other of them? It looks fussy and is irritating to read. And the s/he form is hard to read and should be avoided.

Usually there are ways around the problem. One way is to omit the pronoun altogether. Instead of saying When you visit the doctor, ask her or him to give you a prescription, you can say When you visit the doctor, ask for a prescription.

Often you can change the noun into a plural. So, instead of saying When you talk to the shop assistant, always be polite to him or her, you can say When you talk to shop assistants, always be polite to them.

Another way is simply to use the third person plural as a singular. I talked about this in the grammar chapter. So, instead of saying When someone gives up her or his seat on the bus for you…, you can say When someone gives up their seat on the bus for you… .

Yet another way is to alternate between he and she throughout your document. This still jumps out at readers, but it is becoming more common.

If you find yourself stuck with something that looks ugly, or you are not sure it is grammatical, feel free to change the entire sentence or paragraph around. Remember the apocryphal story about a zookeeper asking for more than one mongoose. First he wrote Please send me two mongooses. That looked strange, so he tried two mongeese. Finally he wrote his letter asking for just one mongoose, but he added a postscript which said Please send me another mongoose too.