To find out their customer service and tech support services, you can contact other customers and know about their satisfaction with quality of service. At the same time, technical support should be available 24×7 including holidays. Also ask for their average response and resolution time.
I would like to add here that I am +1 fully satisfied GTHost.com
vps hosting user. My website is wordpress blog and these guys have all the useful features and tools for running my site successfully. The network uptime is really perfect cos it is always online. I have no outages during the time I have been hosting my site with them.