To continue with my recent post on GMing Basics, here are a few more quick things that are useful advice for new GMs and good things to refresh in the minds of experienced GMs...
Say YES Or Roll the Dice
Probably the most frequently-asked question that a GM hears from a player is "Can I do (x)?" As a general principle, the GM should answer this question with YES as much as possible. Players like to hear that their characters are capable and have agency in saying how the game unfolds. They like to know that they can make a contribution to the game by their decisions -- whether they're a matter of choosing a course of action or merely doing something with style. Saying YES empowers the players and makes them know that their contributions are welcome.
Sometimes you have to say NO, because something is clearly unreasonable or impossible. No matter how many times Rabbi Goldstein punches the brick wall, he's not going to smash through it unless he is a gamma-powered rage monster called The Incredible Rabbi Goldstein. But saying NO shuts people down, and you shouldn't lean on that crutch too much. If players are asking a GM regularly for things that the GM doesn't see as do-able, this is probably based on a fundamental miscommunication about the way the game world works.
The best solution to having to say NO absolutely is to let the dice decide. When the players ask to do something difficult, or unlikely, ask them to make a roll to see if they succeed or fail. You can even make it a tough roll. A small chance of success is still a chance, and doesn't have the same baggage as shutting a player down.
ONLY Roll the Dice If Success OR Failure Is Interesting
The other side of dice rolls is not to ask the players for a check if you're not prepared to accept any outcome that is possible. If the players' failed rolls mean they miss a clue that will stop the action cold, then don't ask for a roll - just give them the clue. There is nothing more boring than everything stopping because of the whimsical nature of dice. It's much better to not ask for a check at all than to call for a check and then have to soft-peddle the results or cheat them somehow to protect the players from a difficult / boring result.
Sometimes a Failed Roll Doesn't Mean Failure
Failure can be interesting, if it adds more complications to the
lives of the players. Maybe a failed Stealth roll could lead to a
pulse-pounding chase or a battle. Unanticipated twists in the action are part of the point of rolling dice at all.
The other way of approaching this situation is to allow the player to succeed, but at some cost to them. So perhaps the player character who failed the Stealth roll manages to quickly hide before the guards appear, but drops something important to them for the next part of the mission, increasing the difficulty slightly. This is a good thing to negotiate with the players.
No Plan of Action Survives First Contact with the Players
Players make decisions that no GM can anticipate. This is a good thing. Although it is unnerving for a novice GM to see their carefully-planned adventure being approached in chaotic, unpredictable ways, player agency is what makes roleplaying a vital form for storytelling. The lack of control over what direction events will go makes gaming fun.
It's a classic rookie GM mistake to plan things out too much, with little room for the players to come up with creative solutions. The instinct to steer players along a set path is a wrong-headed one, because eventually players realize that they are just along for the ride. This is called railroading.
Create Situations, Don't Assume an Outcome
The solution to the above problem that experienced GMs eventually arrive at is to create interesting situations for the player characters to be involved with, but without a particular expectation of an outcome. This is ideal because it places great weight on the actions and decisions of the characters - which is as it should be.
The more charged the situation, the more interesting the fallout will be.
The Importance of Pacing Cannot be Overestimated
I always find it's handy to keep a clock somewhere in my frame of vision and have a sense of the passage of time during a game session.
Try to stay mindful of how long scenes are lasting, and make sure to move things along if not every player character is included in what's been happening. Players are patient to a point while watching scenes with their fellow players in them, but they want to play and be included too. Share the spotlight around equally. And pay attention to what the players' reactions are -- if they aren't enjoying a scene, try to cut it short. If they really dug something, make a note to do more of that in the future.
Be aware of when your end point is, and structure the session so that you get in all of the material you need to within the time frame you've got. I usually have an idea in mind for a final scene that will put a nice cap on the evening and keep my players excited for the next session, and end with that.
Take a break half-way through the session. This is a great opportunity to catch a breather, have a snack, touch base with the players (or eavesdrop on their conversations about what's happening in the game) and get ready for the second half of the session. Seriously. TAKE A BREAK.
If the action is flagging, have something happen to pick up the pace and get all the players on board again. This need not necessarily be an action scene -- Lester Dent says that when the action flags, you should have a guy with a gun kick in the door -- but something that changes things up and kickstarts the fun. I try to keep a list of a few things that could happen at any point in a session, and drop them in as needed.
Don't Be Afraid to Make Mistakes
You will make mistakes, but don't sweat it. As long as your players are having a good time, they'll forgive you any other mistake you might make. If you make a big mistake with the rules, just clarify it after the session or before the next one. If you goofed on an important detail, just openly admit your mistake and tell them the facts as they should be, and move on.
There is little value in pretending to be infallible. A GM that is transparent and admits errors (and does his best to correct them in the future) generates greater trust and amity at the table than one who cloaks himself in authority and blusters at anyone who questions it.
Don't dwell on your mistakes (or allow others to turn them into a big argument / drama). Make a judgement, clarify if necessary, ask for others' thoughts if you're uncertain, and move on.
Make the Stakes Clear
Communication in roleplaying games is really key, and nowhere does this create more strife than when a player finds themselves in a situation they didn't expect as a consequence of their actions. The GM must always make it crystal clear to the player what the results of a decision could be. Is this fight to the death? Could denying the king's request lead to a civil war in the kingdom? It's best to be as transparent as possible about these things.
Remember, it's not your job to talk them out of making bad decisions or protect them from bad things happening -- it is your job to make their decisions significant. Choosing to run the Cardinal through with your rapier when you know it will mean a lifetime of hard labour on Devil's Island is much more interesting than running him through and being surprised when the authorities clap you in manacles.
Sharing Is Good
Whenever possible, include the players in the process of describing how the game proceeds. Let them describe the outcome of a successful roll, or how they dispatch an enemy. Let them embellish their characters' actions and make them their own. Allow them to add details to scenes, or even call for whole scenes of their own. Include them in scenes featuring other players by allowing them to take the part of NPCs in those scenes.
Sharing narrative authority with the players increases the level of trust and involvement around the table for everyone. It is probably the most important innovation in gaming over the last decade, and one of the things that make gaming at out table more fun and rewarding than any I've done in the past.
Don't Be Afraid to Break Your Toys
Last thought: Play hard. Or, as Graham Walmsley would say, Play Unsafe.
It's way more interesting to play a game for four sessions and have those sessions be full of excitement and drama than it is to stretch out a game over ten or twenty sessions and have gameplay drag. GMs should not be worried about their setting being damaged or broken because of player changes. They should embrace change and keep the stakes high constantly.
In Joe McDaldno's great indie game Monsterhearts, he says the GM should play NPCs like they're stolen cars. In other words, don't worry about them getting banged up or even smashed into the wall at 200 MPH. Don't worry about keeping them around forever -- they're not pets, they're just there as elements in a game. Have fun with them and move on.
This attitude is one that players pick up on, and translates into risky, exciting play at the table. If the players know the GM is setting the stakes high and isn't afraid to kick the status quo off a cliff on a regular basis, they will do the same. And the basis of dynamic, exciting gameplay is exciting, dynamic characters.