For a large majority of SQL Server installations, the most important best practice is to use auto create and auto update statistics database-wide. Auto create and auto update statistics are on by default. If you observe bad plans and suspect that missing or out of date statistics are at fault, verify that auto create and auto update statistics are on.

An alternative to enabling auto create statistics is enabled or make sure to manually create statistics using CREATE STATISTICS or sp_createstats.  Note that auto-statistics will not work for read-only databases.