++

sanitize scripts are a must! Also remember to nuke log-files or anywhere else PII or other sensitive info might reside.

You also need to remember the clone will have the same system name, fixed IP if assigned, etc. So bring it up in a private network (easily facilitated within the host system on most virtualization plaforms) or 'off' the network entirely, (controlled from VM settings, no need to go 'pull the net cable' physically) and change those values so you don't conflict with the system the clone was made from.

Regarding testing... I could go on for a long time.. VM's absolutely rock for testing. I've gone entirely virtual for this, and I never want to go back to physical machines unless there's no way around it.