There are several variants of English, with different spellings for the same word. Where spellings differ, use the American English variant. “color”, not “colour”, “rationalize”, not “rationalise”, and so on.

Do not use contractions. Always spell the phrase out in full. “Don't use contractions” is wrong.

Avoiding contractions makes for a more formal tone, is more precise, and is slightly easier for translators.

In a list of items within a paragraph, separate each item from the others with a comma. Separate the last item from the others with a comma and the word “and”.

For example:

Is this a list of three items, “one”, “two”, and “three”, or a list of two items, “one” and “two and three”?

It is better to be explicit and include a serial comma:

Do not use redundant phrases. In particular, “the command”, “the file”, and “man command” are often redundant.

For example, commands:

Filenames:

Manual page references (the second example uses citerefentry with the &man.csh.1; entity):.

Always use two spaces between sentences, as it improves readability and eases use of tools such as Emacs.

A period and spaces followed by a capital letter does not always mark a new sentence, especially in names. “Jordan K. Hubbard” is a good example. It has a capital H following a period and a space, and is certainly not a new sentence.