Begin by compiling a list of facts to include dates of birth and death (if applicable), place of birth and parents' names. Add dates of school attendance, graduations and marriage, as well as information about the spouse and offspring. This fact becomes the outline from which the informal biography will emerge.
Expand the outline to include interesting facts about the subject---recorded information about the climate conditions of the region at the time of his birth or family relationships, for example. This information can be provided by family members or friends.
Education, career, upbringing, special interests or talents should be highlighted. If writing about a man who lived many years ago, provide information on education and livelihood which might illustrate his personality. If writing about a woman from the past, include whether or not she was formally educated or worked outside the home, as well as specific attributes that provide insight into her character. These topics provide the "meat and potatoes" of the informal biography.
Compile anecdotes to intersperse among the facts. Search your own memory or speak with friends and relatives of the subject for their insights and memories. If still living, the subject of the informal biography can provide a great deal of this information. Anecdotes add humor and are considered "spices" of the biography.
Culminate the informal biography in one of two ways: if deceased, mention cause and date of death, summarize the subject's life and reiterate his influences on others, the community, work or family; if still living, briefly revisit the highlights of her life so far, and speculate as to her impact on the future.
Save the informal biography to a computer file or disc, so that it may be added to, edited or published for future generations to read.