Set hibernate.cache.region_prefix in your configuration. It makes it simple to ensure the different session factories don't step on each other if they share a JBoss Cache instance.

Always set up an eviction region for the /TS FQN that uses the NullEvictionPolicy. This will ensure that timestamps never get evicted. Even if you are not doing query caching or aren't caching timestamps in a particular cache, this is still a good practice, as it costs almost nothing and helps to ensure that timestamp eviction doesn't slip in unnoticed later.

Assign a region to your entities, collections and queries rather than relying on class names to compose the FQN. It makes it easier to set up eviction, and helps prevent your eviction setup breaking if class names are refactored.

Assign a different region name to your entities, collections or queries that have different desirable eviction characteristics. Put objects like often used reference data in one region, data probably only accessed by a single user in another. Aggressively evict the latter region; be less agressive with the former if you evict it at all.

In some cases, there is an external application (i.e. outside of Hibernate's control) that can modify data in the database. Generally, a Second Level Cache should not be used in this sort of case, since it can result in data in the cache being out of date with respect to the database. But sometimes application designers can tolerate having out of date data in the cache. In this sort of situation, use an LRUPolicy with a fairly low maxAgeSeconds. This will ensure that out-of-date data eventually gets flushed from the cache.