As with all articles on Wikipedia, articles about saints must maintain a neutral point of view, be composed of information that is attributable to a reliable source, and must not contain original research.
The biographies of saints present a particular challenge, in that it is essential that the historical information concerning the life of a particular saint be separated from information about the veneration of this person as a saint in a given religious community or denomination. If in doubt, one way to achieve this clear division is to divide an article into two parts: Life and Veneration.
However, saints are so diverse, that standardization cannot be pushed too far. Saints vary from important historic figures (popes, kings, philosophers, etc.) with well documented biographies to completely legendary ones. Therefore physical division of an article may not always be very practical. But even then there should be no doubt as to what is a historical fact, and what belongs to legends and tradition.