I recently had a discussion with colleague Arijit Chowdhury on Best Practices surrounding classification in SDL Tridion Sites (Categories & Keywords in the Content Manager and Taxonomy, or the ability to retrieve classified content in Content Delivery).

Note that I've mentioned a few times that I'm wary of the term "best practices" since they could be wielded without context or followed blindly. Context and strategy are important and there are times to completely break a best practice or to revise them. So let's start with at least some practices.

Some Practices

With that said, I'd like to share some hopefully Good Practices I've used with Categories and Keywords that have worked for at least some of our customers.

These are some general tips for implementing and managing classification in Tridion.

• Set Read permissions for all Categories for everyone, to avoid issues with content creation
• Set Write only for select users to limit who can make Keywords to offer centralized control of Keyword creation
• Place default, BluePrint-wide (or "System") Keywords higher in the BluePrint at the Schemas level or higher. These are keywords typical users should not change.
• Manage "Content" Keywords in the Content Publication (or not if users might make random keywords. This lets you translate or localize Keywords from the right level.
• Set Default Keyword selections when possible to guide users to good choices
• Use the Tree View picker to better visualize and group up nested Keywords
• Schema fields can restrict values from a Category -- if the words have a different meaning or I needed a completely separate set of fields, I've created multiple sets of Keywords (US States for Newsletters vs US States for Documents)

You could also use metadata to relate Keywords and maybe handle synonyms. Also keep in mind that Keyword keys (see frank taylor post on Categories & Keywords) can represent the "programmatic" identifiers for some text and are unique within a given Category. You can use Metadata or Titles for translation instead.

Out-of-the-Box Taxonomy Functionality

In addition to implementation practices, your users might find Taxonomy tagging, Advanced Search, Virtual Folders, and Bundles helpful to find, organize, and adjust "tagged" content or pages.

Taxonomy Strategy

Sometimes an implementation might find unwanted Keywords or mis-tagged content in their implementation. 

For times when you have large maintenance tasks ahead of your or say, "content or classification debt" the advice I've heard/given is to:

1. Stop the bleeding
2. Fix/address the backlog over time

This might be familiar to anyone that's tackled an ongoing challenge like accessibility, compliance, broken links, bugs, technical debt, etc.

For issues with Categories and Keywords (or Taxonomy) consider starting with a way to measure the impact or create reports. Then the maintenance "phase" happens over time and tied to some performance metric, report, or dashboard as part of your standard operating procedures or definition-of-done.

If looking for more non-technical advice, find your closest Information Architect or Content Strategist!