The UOC recommends using gender-neutral language. For example, to refer to a person whose gender is unknown to you or not of concern, you can use the pronoun they (or its inflected forms their, them and themselves):

This contrasts with use of the masculine forms he, him, his and himself in circumstances such as these. In the 19th and 20th centuries many grammarians prescribed this approach but nowadays it is recommended less often:

There are differences of opinion regarding the approaches described above. The view from the UOC Language Service is that arguments in favour of the so-called singular they (for example those provided by Purdue OWL or the Oxford English Dictionary) outweigh arguments against it (for example this opinion piece published by The Atlantic).

If you feel unsure about which third-person singular pronoun to use, bear in mind that it may be possible to avoid the third-person singular altogether. By making the entire sentence plural our example becomes:

Another option is to omit reference any person at all, particularly when it would not add information that cannot be otherwise inferred. For example:

When the sentence in question provides instructions, you may also consider using the gender-neutral you or an imperative formulation. Examples:

Finally, on rare occasions, constructions such as he/she, s/he or he or she (or the corresponding inflected forms) might be used, thus giving, for example:

Bear in mind, however, that these types of construction are non-inclusive towards people whose gender identity is non-binary and their repetition can make a text sound stilted. It is therefore best to avoid using them. 

In many cases, gender-neutral terms now exist for traditionally gendered expressions. Examples:

Generally speaking, the UOC prefers to use gender-neutral terms when possible and natural. Use your best judgement for when their use might be appropriate.

In contrast, be sure not to re-gender sentences that already use gender-neutral terms by adding gendered phrases. For instance, phrases such as male nurse or female executive, which may unwittingly reinforce sex-role stereotypes, should be avoided unless the author is intentionally drawing a distinction based on gender. Even then, the sentence can often be restated in a more gender-neutral fashion. For example, the sentence Female executives account for only 30% of the total number could be rewritten as Women account for only 30% of executives.

Where it is necessary to include such a phrase, use the modifier female or woman/women rather than lady or girl to avoid negative and/or dated connotations.

When it is deemed absolutely necessary to use both a masculine and a feminine term, be sure to alternate which comes first. Example:

Alternatively, in some texts you may be able to alternate between examples involving one gender and examples involving the other. Texts about parenting, for instance, often use alternating examples involving daughters and sons. That said, this usage can be confusing and it is thus essential when following it to ensure the coherence and readability of the text as a whole.

The recommendations given on this page are also summarized in this infographic.