There is some really good commentary and discussion here!
I now want to address Foote (and other people in a similar position; I know there are a bunch of you!). The SC RPG Starter Kit, and the other adventures we are going to release for this game, are exactly what you want to make things less daunting. To explain what I mean, I'm going to talk about my general approach to GMing, in particular for story-driven RPGs like Sentinel Comics. Although this might sound daunting, I'm *then* going to explain how the adventures we are making are going to remove most of the daunting work, and make it easier for you as a GM :D
1) Make sure that all of the players have characters that are fun for them to play, and have reasons to work together.
This relates to the comments above about the "social contract" between players and GM. As the GM, I believe it is my job to craft a story/setting that will be fun for the players, and give them all interesting things to do. I also believe it is my job to make sure that the players all create characters that have motivations and desires that are at least somewhat compatible. To this end, I'll generally have the players create their characters before I solidify the adventure, and I'll give "soft" restrictions during player creating if I think it is necessary, or guide player creation until they come up with something I can work with (often using the "yes, and" techniquie from improv). For example, I might say that all of the players in a Star Wars campaign have to have some reason to be working for the Hutts, or to be Imperial officers; or in a D&D-like setting, I might say that no one can be Evil, or maybe even restrict Chaotic Neutral if I know that'll be a problem.
FooteNote:The Starter Kit solves this for you! We will provide premade characters who all have reasons to work together (they are the Freedom Five!).
2) Craft scenarios where all of the characters have something to do that interests them.
Let's use the example from above! PlatinumWarlock proposed the following situation:
Jim makes a character designed to follow in Bunker's footsteps; he's interested in dealing a ton of damage, fighting a bunch of bad guys, and stomping on robots in a mecha-suit. Amy makes a new Virtuoso of the Void; she's more interested in exploring the relationship between the Virtuosos and Akash-X, as well as interacting with other heroes (and even villiains).
There is actually a lot to work with there. The nice thing about a comic book setting is that it is easy to tell players that they have to make characters that think of themselves as heroes, and generally act in a heroic way. In the above setting, I'd likely create a scenario where some kind of villain wants to harvest power from or otherwise damage somewhere important to Akash-X and the Virtuosos; maybe somewhere attuned to void power. I'd likely also make their scheme involve tapping into the power of the Void and/or the past Virtuosos. Then, I'd make sure that they had some sort of violent means by which they wanted to accomplish their ends; maybe Professor Pollution is back with some PollutionBots that are out to kill all of the local fauna, or maybe the antagonist is Citizen Dawn and a bunch of Citizens. Either way, there'd be a situation where both players have lots of hooks for their characters, and will each get turns in the spotlight.
FooteNote: Again, the Starter Kit solves this for you! Since we know that the characters will be the Freedom Five, we put them in a scenario that they'll inherently care about.
3) Know your world.
If I were to run a game in the Dune universe, I could fake it if my PCs didn't know much about the world, but I'd have a hard time. I'd really want to go and read some more dune books and talk with our Inventory Manager for many hours to prep. However, if I'm going to run a game in the Star Wars universe, I just pick a starting portion of the galaxy and run. If the players decide that the place I planned for them to be (say, Hutt Space) is not for them, and decide to run off somewhere else (say, Corellia), I've got a decent idea of what's there, which is enough to bluff my way through the session and describe some stuff that the PCs see when they show up. I can then just pop over to Wookiepedia between sessions and come up with some more detailed settings. Knowing your world is also of course doable if you create the world from scratch, but it is actually a lot harder; not only do you have to craft the world, but you are the only source of world information, so if you haven't prepped something for an area, you don't have a wiki to fall back on.
FooteNote: Here's a quasi-secret - one of the major reasons we started releasing The Letters Page now is for background/worldbuilding for RPG players. If you listen to the podcast, you know more than enough about the world of Sentinel Comics to run an RPG. Relatedly, we recently made the Sentinel Comics wiki officially supported by GTG, and it is a great source of info!
4) Know the game rules
As the GM, you are the arbiter of the rules. It is important that you know them fairly well so that you an answer rules questions from players. It is also important to be confident; if you don't know a rule, it is generally better to guess (and stick with that guess during the session) rather than pause the game for 5+ minutes to look something up.
FooteNote: This is the main thing you'll have to do in order to run the Starter Kit. Fortunately, the rules for the Sentinel Comics RPG are much simpler than many other RPGs. So simple, in fact, that the rules document for the Starter Kit can fit in a short, staple-bound booklet. If you can understand the rules for Spirit Island (to say nothing of Galactic Strike Force), you'll have no problem with the RPG rulebook :)
5) Prep Settings/Scenes, not plots.
In my experience, preping entire plots, movie-style, is way too much work and often a waste of time. In an RPG, Players have agency, and PCs will definitely jump in all sorts of directions you don't expect during a long campaign. Instead of saying "no, you can't do that", you really want to be able to use the old improv trick and say "yes, and then this happens". To accomplish this, I tend to create antagonists who have their own goal and plans, and then put the heroes in a situation where they will want to do things that intersect those plans. I'll then prep specific scenes, but not how I envision the plot proceeding. For example, I might decide that Citizen Dawn is going to invade Megalopolis, hold the City Council hostage, demand gold, and have some Citizens start blowing up infrastructure. I'd prep 2-3 different "citizens are blowing up infrastructure" scenes, a City Council scene where Dawn is making demands, and a scene where the gold is being delivered. I'd then introduce it by saying something like "You're sitting around Freedom Tower when you feel a huge explosion. Looking out of the 34th story window, you see smoke rising from the power transfer station down on 101st street*. What do you do??". The players then have a reason to investigate the explosion, and on the way might see some other suspicious stuff that will let them work out what is going on. I'll then have a rough idea of what I think Dawn and the Citizens will do in any given situation, so I'll just have them react on the fly accordingly, with no specific plan for how the situation will end.
FooteNote: Running a story the way I just described definitely takes practice. However, the Starter Kit is specifically designed as GMing 101, with a story that is fun to play, and is presented to the new GM with sort of "training wheels" for the system. There is a lot of room for player choice, but the plot branches are constrained by the story, and the Starter Kit walks you through letting the players do things in any order they choose.
Final Thoughts
- Play to your strengths. If you are not good at voices or dialogue (I'm not!), don't bother with it! If you are, do it up!
- Don't worry about getting all of the rules right; just worry about making it fun.
- Lean heavily on stuff you already know and work other people already did.
*All of the geography of Megalopolis and Freedom Tower is non-canon stuff I just made up as I was typing. 75% of GMing is making up plausible-sounding BS on the fly.