This has been part of my regular job.
Good Communication skills because support is expected done remotely as well.
Good knowledge and experience on Windows Desktops & Servers installation and troubleshooting.
Network troubleshooting that includes DNS, DHCP & NETBIOS
Good knowledge on MS Office tools installation & troubleshooting.
Good knowledge on tools such as antivirus, browser, VPN software etc
Prior working knowledge to deal with B2C clients.