Typically I find using the placeholder text as an example of the intended content is best. So, the label describes the field, and the placeholder exemplifies the type of content.

Here's a good example, from this article: http://www.pardot.com/faqs/forms/placeholders-and-labels/

placeholder text in field http://www.pardot.com/help/wp-content/uploads/2012/06/placeholder6.png

Typically I find using the placeholder text as an example of the intended content is best. So, the label describes the field, and the placeholder exemplifies the type of content.

Here's a good example, from this article: http://www.pardot.com/faqs/forms/placeholders-and-labels/