Remote administration of workstations

Our windows domain is powered by windows 2012r2 servers. We have a mixed bag of windows 8 and windows 7 client workstations. I would like to administer these workstations remotely, the same way I administer the servers. I want to be able to use remote desktop, use regedit remotely, use the VAMP tool, things like that. I have created the WinRM group policy but things just aren’t working. I don’t want to have to physically visit every computer in the domain. I am missing something but I don’t know what.