She/he/they
When writing more generally, use the singular “they”.
e.g. Instead of writing, *If an employee has a problem, he should see his HR manager”, write, “If an employee has a problem, they should see their HR manager.”
It is not acceptable to use a masculine pronoun or adjective as the generic form standing for everyone. Please do not write “s/he” or “he/she” either. Instead, you should (a) make the noun plural, (b) use what is known as “the singular they” to denote someone who may be either masculine or feminine, or (c) alternate between the masculine and the feminine forms chapter by chapter.