I have been involved in virtualization projects for about ten years now. In that time I have had the opportunity to track my own list of best practice items. It's a list I share freely with customers that seek out virtualization advice. I can tell that virtualization (and Cloud) efforts are on the rise simply by the number of requests I get for help, specifically for virtualizing SQL Server.
I like to call this list my "facepalm" special, as any one of these essentially triggers a facepalm reaction. They have helped my customers in the past and I am certain they will help you.