I was preparing for an online game and I got to thinking I could share how I prepare for online games.
The first thing I do is consider the time slot. A lot of games at conventions are given a time slot. I think it is rude to run a game that exceeds the time allotted, unless everyone at the table says to continue. This is because it could cause people to miss out or be late on their other content. Sometimes people get nervous when the rest of the group starts clamoring for more and do not feel comfortable in saying so and are late for their next event. It is also rude to run your game below the time allotted, this is especially true when people have paid for your event. No one likes to feel like they haven’t gotten what they paid for, so you want to avoid that.
When you consider the time slot, you need to consider what type of adventure you are going to run. Is it combat heavy? Are there tricky puzzles? What areas are going to boggle the players? Do you know what type of players you are going to have in your game (experienced/new rowdy/quiet)?
Once I have considered these kinds of things, I pick a module or write up my own adventure that meets the parameters of the online game. While prepping, stay alert for things that could be triggering for players, ex. a pit full of snakes. Look for places you can add or delete content if time is at a premium during the game. Just like a face to face game, online players can get bogged down by dungeon dressing like shiny stones. If this happens just close off that hallway in the north half of the map. I would encourage you to just grab a random map from another adventure that is in the same genre as yours and have it on hand along with some randomly generated monsters, just in case.
I don’t usually run with an online tabletop but if you do, you will need to prepare it, this takes time. Learn your VTT! It is very humbling to have your players know more about it than you. Play around with the lighting options and see how your map works out. A bad thing about online tabletops is that if you need to improvise and add or delete rooms for time, it can be hard do this discretely.
Similar to knowing your VTT, know your video/audio communication program. If it is a Zoom meeting, has the invite went out to everyone? If it is Discord, have you been chatting with everyone in advance of the game? Also is your camera and microphone working? You may need to close out other background apps.
When I prepare for online games, similarly to how I do in face to face games is to print out a copy of the adventure map that I can have for reference without having to worry about the book losing its place. I am old school and use notebook paper to write a sentence or two about each room. For monsters in the rooms, I put their senses (perception, vision level), initiative modifier, hit points, and their basic attack and damage along with a page number for their full stat block. I do this because those are the most normal stats that are required. For combat tracking I use the Pathfinder Combat Pad, but sometimes I just use a legal pad.
That is how I prepare to run an online game.