Wikipedia:Gender identity

MOS:GENDERID states, in regard to terms relating to gender identity:

Give precedence to self-designation as reported in the most up-to-date reliable sources, even when it doesn't match what's most common in reliable sources. When a person's gender self-designation may come as a surprise to readers, explain it without overemphasis on first occurrence in an article. Any person whose gender might be questioned should be referred to by the pronouns, possessive adjectives, and gendered nouns (for example "man/woman", "waiter/waitress", "chairman/chairwoman") that reflect that person's latest expressed gender self-identification. This applies in references to any phase of that person's life, unless the subject has indicated a preference otherwise. Direct quotations may need to be handled as exceptions (in some cases adjusting the portion used may reduce apparent contradictions, and "[sic]" may be used where necessary).

While many varied viewpoints were voiced in formulating that guideline, this essay outlines some of the commonly recurring views that helped shape it, and answers common questions that are raised in regards to it. For more on transgender issues, you may want to check out the American Psychological Association's "Answers to Your Questions About Transgender People, Gender Identity, and Gender Expression".