Virtual Disk Provisioning and Memory best practices for VMware Virtual SQL Servers

is it really Best practices and better, to use Thick Provisioned Virtual Disks on VM's that will be Microsoft SQL Servers?

 Also is 6GB of memory too low for a virtual SQL Server?

I am asking these questions because in our current environment i am noticing alot of VM's that are SQL Servers with Very little ram and also noticiing the Virtual Disks are all Thin.  

Our LUNs on the SAN side are all thick just an FYI.

From my understanding, i was told always use THICK for SQL, and i have never seen a sql server with only 6gb of ram.  I know there are ways to have SQL use less ram from within SQL itself.  

Just want a confirmation on the best practices, and real life experience.

Thanks