Place a comma after the day when writing a date out in long form. For example, the comma would come after the number 29 when writing November 29, 2011.
Use a forward slash to separate the numbers when using numerical reference for month, day and year. For example, a forward slash would go between 12, 18 and 11 in the date 12/18/11 or December 18, 2011.
Change the forward slash to a period or dash between each of the numbers when using numerical references. In the example above, you could change the slashes to periods for 12.18.11 or dashes for 12-18-11.