Tip 1: As you come across dates to record in your information, it is good practice to record them in standard format: day of the month, month, and four-digit year, 18 Oct 2012. This way there isn't confusion as to whether something happened on April 11 or November 4 for a birth date written 4-11-52. It is also clear that something happened in 1952 rather than 1852.
Tip 2: Sometimes the date you locate is exact, a marriage license signed by the Justice of the Peace on September 5, 1926. Record this fact in standard format, 5 Sept 1926. Other times, however, a date isn't so precise. Often census records only show a person's age at the time of the census, i.e., your uncle Jimmy Smith was listed as 17 in the 1930 census. In this case, make use of the term circa and record his birth date as c1913 or ca1913. Later if you find his exact birth date, you can record that date in standard format.
About.com had additional information on writing dates using standard format.