The heat loads of servers and storage devices are continuing to increase at a rapid rate. These increases are causing data center operators to struggle with how to provide adequate cooling for these high-powered racks. Over the past four to five years there have been a number of journal articles published related to the cooling of high-density data centers. The purpose of this paper is to review all of these articles and capture the recommendations/guidelines that pertain to best practices for cooling racks in a data center. This paper contains a review of 83 papers covering primarily a time span of 2001 to the present. The best practices are divided into categories that are then easily implemented by the data center designer or operator.