Get started with Hadoop: From evaluation to your first production cluster by Brett Sheppard.
From the introduction:
This piece provides tips, cautions and best practices for an organization that would like to evaluate Hadoop and deploy an initial cluster. It focuses on the Hadoop Distributed File System (HDFS) and MapReduce. If you are looking for details on Hive, Pig or related projects and tools, you will be disappointed in this specific article, but I do provide links for where you can find more information.
Highly recommended!