I'm copying some text below from some of my earlier posts with some stuff that might be useful. Saving myself some typing.
There's 2 essential parts to a typical shadowrun: Meeting the Johnson and penetrating a security system. There's a 3rd part that is optional, but fairly important, the legwork section.
Meeting the Johnson usually is done at a bar or night club of some sort, often in the back room, but this is not a set rule. There is sometimes a meeting with a Fixer first, but often this is done by phone/text. The runners get the vague outlines of the run, decide if it's something they want to do, and if so then negotiate a price. At this point the runners are given more details on the job and can ask questions. The Johnson sometimes provides help with the run or sometimes will provide it if asked. (Fake key cards for example to get in the target site) This is a great time for a GM to help out beginner players with ideas on how to infiltrate the site.
Instead of a dungeon full of monsters, shadowrunners penetrate security systems. This is usually to get into some building or group of buildings. The basics you need to have is a layout or at least a general idea of a layout, guard stats and patrol habits, command centers and other large groupings of guards, physical security (ie drones, cameras, motion sensors, fences, and more), magic security (if any), and matrix security (If any, usually at least a small amount) You also want response times both for the police and any additional security the site has contracted. (Could be their own forces somewhere nearby or some other contracted company) The generic shadowrun is the runners breaking into a building to get a hacker to an offline system to steal paydata. But sometimes the target is something physical. And kidnapping valuable employees for a "career change" is another common shadowrun.
The third optional part of a shadowrun is the legwork section. Not strictly necessary, but it makes richer stories and it lets certain character types like Faces get a moment in the spotlight. This is mostly meeting with contacts to get information about the run. It may involve solving a mystery or it may involve things like learning the physical layout of a target. Sometimes an entire shadowrun can be mostly legwork. For example, you are hired to find some rich corper's runaway son or daughter. (The legwork section of the run usually is set before the security system penetration)
(From yet a different post...)
You should have stats for every NPC they might fight on site. In addition you want stats for any possible responding forces or police. You also want social stats for any guards, receptionists, or other npcs they might have oppose on the social level, such as conning their way past the npc to avoid a high security chokepoint. In addition, it's a good idea to have some stats for really typical npcs in the world on hand, just in case. Typical ones include police officer (Lonestar or Knight Errant), typical security guard, typical ganger, and typical lieutenants for all these types. You probaly also want some elite forces ready, especially for the police. You probaly want some drone stats too, especially recon drones as they are often first responders for many security services.
Best bet is to try out a few test runs using only the book archtype characters. Keep it simple and introduce combat and social skill basics first. Then introduce magic and breaking and entering skills. Save more complicated parts of the game, such as the Matrix and vehicle combat for later. Once you have magic and combat and skills down, then have them make real characters and start the real campaign.
Your best bet is to go easy at first and focus on story telling. You can also use tension encounters to liven things up without killing everyone. For example, the cops pull them over. No combat happens unless the players are dumb enough to set it off, but it livens things up a bit. It's quite easy to become a killer GM in Shadowrun, so go easy, at least at first. Remember many of the lower level corps use non lethal measures with their security guards. (As opposed to the sadistic and wealthy MCT goons who love killer drones and deadly nerve gases)
There isn't really a set limit on how vast a campaign goes. But this is a dystopia and generally the runners don't take over the world. It's a huge victory if they survive 5 years in the shadows and retire. Many many runners die in the first year. It's usually good to break things into seasons like a TV show, with a big story arc to go along with it. And campaigns sometimes end suddenly, so this way if that happens you at least got to tell a few story arcs.
I suggest always having small shadowruns on hand to run. These can be extremely basic. The point is you can use them to speed up a session that is running slow and also they make sure you are never empty handed. Also some books that I've found extremely useful for creating stories are the 2nd, 3rd, and 4th edition Seattle guides. Each of the edition has different things in it that I found of great use. 1st edition sprawl sites is also excellent for run ideas. The Genesis shadowrun video game can give you some ideas for basic runs if you can find a copy or emulator. I'm sure the new Shadowrun Returns game will have some great run ideas as well.
