While I see your point taibhsear, the biggest hurdles to online DMing come with making full use of whatever interface you're using, and depending on the DM's style, that can be almost entirely avoided. The more you rely on theater of the mind, and less on battlemaps and such, the easier it is to adjust to the new platform in baby steps. Figure out character sheets and how the configurations on them work, and build your way up to fun map construction and macros n such. Really, I learned very little about the Roll20 interface until I started running a game. As long as you're straightforward with your experience, plenty of players will send you macros and help explain things along the way to make games run smoother. The biggest thing players care about is a good story, fun environment, and the creative freedom we all look for in tabletop games.
