Getting geared up for a Shadowrun interlude while DnD is on hiatus. I'm GMing, which I've never done before. I've played a handful of times and it's pretty much the only game that I've read the novels of.
Any advice for GMing? The players are new to SR and newish to gaming (6 months experience each in games)
Shadowrun is probably the easiest system to learn to GM, because each story is entirely encapsulated. You just have a few rules you need to know. It also helps that you know the players will go off whatever rails you set for them, but still try to complete the mission.
For a single session, I'd start with showing an interesting location (Ork Underground, plastic jungles, The borders in Denver, etc.) and some sort of story (rescuing someone who was kidnapped, making sure a singer makes it to their concert, stopping a neighborhood from being demolished for a new corp facility, rip off an action movie, etc.). Find a way that they mesh, and what special things the location changes (low lighting in the Ork Underground, legality issues at borders, different languages/linguasofts needed, etc.). Once you know where they're going and why, you can start setting up the actual run.
What kind of security would make sense in a perfect world for everywhere they might go because they'll start a fight somewhere they shouldn't need to, why don't they have that kind of security (being too cheap, the security they have is old, the security is only partially installed, whoever set it up made mistakes), and the general attitude of the security forces (overconfident, bored, power-mad but miss things). The second part there is where you can tailor the difficulty to the party. You also want to know where all of the entrances are, and where new entrances might get made. How do people who work there normally get in?
Pay special attention to what spells the mage has, and what drones the rigger has. A lightning bolt is more effective against drones and computers, but otherwise doesn't do anything interesting. Invisibility (and is it the invis that works against both cameras and people, or just people) and levitation means you have to know those rules, and what that will allow them to get around. Don't let the mage solve everyone's problems. The rigger might be based on driving fast, stealth surveillance with small drones, or have a small army that can throw down a lot of damage once they're going loud. Try to make sure one scene works for them. Adepts probably have some interesting powers like wall-running or face sculpting, so plan for a scene that lets them do those things. Also, don't plan anything completely. Your players will think of things you didn't, and will just bypass things you planned. Having twice as many things that are half as planned out means more of your work gets used.
Expect combat to be deadly. Depending on edition, 90% of characters can be 2-shot or take down an opponent in 2 shots. Ambushes means one side gets their shots before the other side can defend, so those fights will be very one-sided.
If you know what characters and how many you'll have, we can give more specific advice.
Edit: To make combat less deadly towards the PCs, you will want to make sure opponents are always slightly less powerful than the PCs. I usually ran with 1+ die advantage in favor of PCs, because they need to win every time, where enemies only need to win once. Also, what edition are you running? I'm mostly experienced with 4e, but know some 3e, and enough 5e to know why I don't play it.