Use modules: The /etc/puppet/modules directory allows the creation of modules. Modules are subdirectories created within the Puppet ModulePath directive, and contains files and configurations that need to be distributed to the client as part of its desired state. This simplifies the Puppet configuration, as related files are all within the module directory.

Use version control: Puppet itself does not have version control, but we can use something like GIT or subversion (svn) to maintain the previous copies of configurations.

Style: When writing Puppet configuration, standardizing the syntax style helps in maintenance and readability. The Puppet Labs style guide can be found at http://docs.puppetlabs.com/guides/style_guide.html.