Beings I did strickly test boxes, I didn't dig deep into the do's and don'ts, only what I've done with PS4 on vsphere 4. No more than two vcpu's and 4GB RAM. I always separate my citrix boxes so the OS has the C:\ pretty much to itself, every app I have is installed on separate disk/partition. Again, this ran just fine with test users.
I remember reading a few online blogs about what a guy should do to make sure the citrix box runs as best as it can, but honestly I've never had much luck with any of them. I tweaked our VM's for about a month, found a good point, removed citrix and IIS, cloned it, and stored it. It's worked great for new deployments and it's pretty much your basic install. The only time I've run into problems so far is when I try to get to many users on one box.