Yeah, that is one issue that I did encounter at first. Supporting users.
Luckily, since most of the marketing comes from word-of-mouth, a lot of users have a decent knowledge of Linux / VPS'.
I also make Ruby scripts as well as using a crap-ton of custom shortcuts in Mutt (terminal-based email) so answer support tickets quickly and without a ton of effort.
The occasional ticket I usually get involves some form of client-side/user issue such as a borked Linux package install.
Usually I bite-the-bullet and say "We don't usually provide support.. but I would suggest having a look at X or Y on your VPS." 90% of the time the customer fixes it with my guidance and they learn what do to next time it happens. The other 10% I unfortunately say tough luck to and suggest to hire a Sysadmin or I link them to someone who can provide support for cheap setting things up.
Funny enough, most Chinese / Indonesian customers rarely ask questions! Even if they don't speak English well, we can still understand each-other in Linux terms. I don't know if it's a cultural thing, but most Eastern clients countries try and figure the issue out themselves first. Western clients usually open a ticket first, then figure the issue out.