1. Take a class during the planning stage and before implementation to help you define which physical box servers to virtualize, which to wait on, and which to leave as is.
2. Glean valuable information and support for your virtualization project through regional user groups and their message boards.
3. Perform a complete inventory of your servers, operating systems, and applications. Figure out which ones you plan to virtualize. Consider hiring a consultant to help map out the process.
4. Recognize that while many servers can be virtualized, others might have to wait or not be virtualized at all given their age and hardware constraints.
5. Test, test, test. One of the advantages of virtualization is its testing mode. Go slowly.