Make your file system (and version control!) the master of your templates.
ExpressionEngine has basic capability for templates, template partials, and template variables as files, but if you delete a template, template partial, or template variable file from the file system it is not deleted from EE. Or if you change a template’s file extension, it does not change the template type in EE. ExpressionEngine also does not sync System Specialty Templates with the file system. Template Sync makes all of these things easy!