Part of my job at the tiny company I work for is to look after the licenses we sell our customers and to help them get going, or upgrade to newer versions, that sort of thing, and I can absolutely do some of the more advanced tech support for any part of the code that I've actually written (and some I haven't). Throughout the years some customers have gone out of their way to say how impressed they are with the support they're getting, our dedication to quickly finding solutions or going right ahead and implementing a bug fix that gets released within hours of a problem being reported. Those always make my day. I never use a condescending tone, or treat customers like they're idiots, and always try to walk them through solutions just as if I was sitting right next to them at their desk and having a conversation.