This post is definitely going to be formatted poorly. I apologize up front about that.
My friends and I are all big fans of Shadowrun. The setting, that is. We've only ever gotten one campaign off the ground, because only one of us is a really experienced GM, and even that one went a bit sideways. (I moved back up to Alaska and, although the game was online, that meant it was at 6am for me. That is, when I could even make it. Ugh.) That was 4e, and it was probably a half-dozen years ago at this point. Every one of us would be stoked to play in another Shadowrun campaign, but most of us either don't have the GM chops, or don't understand the game well enough. The member of the group with the best technical understanding of the game wants to run a game this summer, but in my experience, anything you plan out months in advance is probably not going to happen. I really hope that isn't the case here, but I feel I should hedge bets, just in case.
The guy that is going to be running a campaign in a bit, I'm not sure how much he's GMed in the past. I know it hasn't been often, at the very least. I've GMed a few campaigns in other systems recently, trying to build up the relevant skills. Mostly Savage Worlds, so a lot more fast and loose. Had an Interface Zero 2.0 campaign that went alright, but it was pink mohawk as all hell. Kept it low level, dealt with washed-out celebrities and gangs primarily. Have a much easier time conceptualizing things on that level.
Anyway, I'm rambling. The biggest hurdle has been poor understanding of the system. I can build characters, no problem. I could probably walk through play, or any individual task, without too much issue. (Except technomancers.) One of the big problems I have is appropriate response. That is, conceptualizing how NPCs should respond on an organizational level. The scale between "we'll send someone to check it out" and "You got five stars in GTA and changing your clothes won't help you." Always super hesitant to escalate, but I've had D&D campaigns, for instance, where a person just ran through a checkpoint, no papers, because "what's the guard going to do?" (Guard attacked, several more gave chase.) Different group, but stuff like that still makes me hesitant. Just seems like that's the kind of thing you have to deal with a lot more in Shadowrun, since players are directly undermining organizations.
I'm committed to learning the system. Even if my buddy winds up unable to run, we're going to have a Shadowrun campaign. I'll strap on my thinking cap and huck fistfuls of d6 onto digital tables.
1: How can I best make myself useful in keeping the game together/on track, assuming my buddy runs one? (What helpful things have players done in your campaigns?)
2: If my buddy can't run, do you have any tips for new GMs? Specifically when dealing with the stuff behind closed doors. I ran a supers campaign one time, probably the only time I've ever had villains with machinations. At one point, said machinations wound up getting a prominent NPC member of the team (secretary?) killed, back at the base while the characters were out pursuing a lead. It was intended as a dramatic shift. Two players got that. Felt like the other two were very much unhappy with it, and not in a "this is appropriately dramatic" sort of way. Kind of killed the campaign because even after they sorted the villain, I felt like the spark was gone.

Want to avoid that without making everything just goofy nonsense, you know?