A client asked: Should I always make backup versions of the XML schema?
When the XML schema is published it re-generates the underlying SQL and .aspx code. If trouble hits, a "refresh" or "rollback" to an uncorrupted schema is always a backup plan. A versioning scheme is also required to keep track of different versions of the XML schema at different points in time.
To make a backup of the schema from within Microsoft CRM navigate to Settings > Customization > Export Customizations. Browse to the location on your personal hard drive where the .XML file is to be stored.
Also be aware of the items below:
Tip #1: Export only the customizations of entities that you customize and keep each entity customizations in a separate file
Tip #2: Put the date on the file names and while you are working you will be doing this multiple times a day.
Tip #3: Don't save this on a Development Virtual Machine (if the VPC is closed inadvertently, the export could be lost)