Reading the log files in citrix cloud is useful, say looking at ICA/RTT latency, maybe figuring out if a problem is with the home user network or work network as oppose to citrix vda issues with networking, perhaps have them learn about how ost files and profiles are on a network drive and how the IOPS keeps it stable with fslogix tech, how to read event logs , use the rda analzyer tool, maybe expose them to blogs - here's the fslogix documentation I used to study when I worked at my last gig -
https://social.msdn.microsoft.com/Forums/windows/en-US/defe5828-fba4-4715-a68c-0e4d83eefa6b/release-notes-for-fslogix-apps-release-2009-29762130127?forum=FSLogix, I'd also talk about the citrix receiver and why the version and it's configuration is important. if you're able to make their jobs easier without too much hassle is key, also it's important to distinguish between level 1 and level 2 and scope out the more enthusiastic types who want to learn new things