If you are wholly new to the game and you are starting as a DM before starting as a player, get some modules.♥︎ Good luck. You’ll do fine.
The following is for people who are experienced players and are now switching over to the DM side of the screen, to shake ‘em out of some misconceptions about how the game is best set up.
Don’t prep scenes, don’t write “scripts”. But do prep places, obstacles, enemies, rewards and situations.
That is the biggest thing that I wish I knew when I went from a player to a DM. The game loop is
That’s the loop, and from that it’s easy as a player to get the impression that “wow, the DM had all these scenes for us, first we met the fishmonger, then the troll, and then we had that fantastic castle, where we first entered the big hall”, it can look very linear, and then when those players become DMs they take such a “linear structure” and try to impose it on their players. This is a common problem, and even commercially available adventure modules are set up this way (and they fall apart as soon as you touch them with a stick). Don’t fall into that trap.
Instead, always think “maps & encounter tables”, not “scene 1 → scene 2 → scene 3”. You’re making a world, not a movie script. Random tables can save you a lot of work, you don’t have to prep every grain of sand on the planet, but interacting with a world that’s “there”, that’s been committed and has an off-screen game state where things are actually canon, where you can actually make an impact, can feel more meaningful than the “shadowboxing” of playing in a world’s that’s being constantly pulled out of the DM’s hat on the fly.
Usually, to answer any questions that come up, like “what’s in that house down the street?” I try to think in three tiers. First, is the answer in the existing prep? Then use it. Otherwise, is there a random table or other mechanic that can generate the answer? Use that. Lastly and only as a fallback, make something up. Don’t feel bad, it’s fine, but make a note and patch the hole for similar situations in future sessions. That way, your DM’s toolbox will gradually grow as you get more experienced. You can start simple and then you’ll know what type of prep you need and how to efficiently patch holes by coming up with mechanics and tables that cover a lot of unexpected situations. My own home table runs a complete hodge-podge of like market availability rules from one game, climbing rules from another, crafting rules from yet another and so on. Don’t get overwhelmed as you start out, soon enough you’ll be able to answer any situation with an ‘of course’ and a satisfyingly official answer.
When you do have to make things up, here’s a tip from my pal Vincent, he says to “give everything a but”. You have some principles about the world and then you constantly nuance them. “This is a rough&tumble world, but this person is vulnerable, trusts you.” “Every pirate ship is old and worn, but this one seems especially so.”
Make sure everything you place on the map has stats, and stick to those stats. When you ask for rolls, state the DC or AC before the dice hits the table.
I know Mercer and Colville does it differently but that’s my advice. Without a stated DC, I’ve been all too tempted to give the answer I want to give, but the reason we roll is for the dice to decide. I also personally never, ever fudge (and changing HP and AC is also fudging)—my players’ characters die all the time but if your group has a problem with that, it’s better to fix that with a houserule that keeps them alive in a way that’s transparent to everyone at the table rather than a decision the DM can make behind the screen. You never want to be in a situation where you are the one deciding who lives and dies, when the game system is designed to decide that and can take that responsibility off your shoulders.
Don’t roll for social situations. I try to suss out who is asking and who would be answerer, and if there would be no objection I just give them the answer right away. If there would be an objection, then what “tactics” would the answerer use to avoid answering? How and why are the NPCs not always giving the PCs what they want? Don’t inject drama where there is none. “Can I buy a healing potion from you for 50GP?” and if the NPC has healing potions for sale for 50GP then the answer should be “Of course, madam, and the bottle’s complimentary!” and move on. Do whatever li’l voices, flourishes you want, that’s up to you. Don’t make a conflict where there’s no conflict.
When there is a reason for the NPC to not immediately give them the resourse or answer, or for an NPC to ask something from the players, and you have that reason clearly in your head, playing out conversations becomes crisp and clear but still sounds natural. The NPC will be convinced if and only if the players can deal with their “tactics” like doubting, lying, disrespect, respect etc.
Like let’s say you’ve noted (or rolled randomly) that an NPC knows the truth, but is afraid to tell it because they think they’ll be falsely accused of being involved themselves. That’s the type of info about an NPC that came make the conversation really come alive.
I don’t do the whole “insight check”, “persuasion check”. The skill system is optional in 5e for a reason. I don’t like “roll dice to solve” puzzle either. Also for searching and investigating. If the key is in the compartment under the drawer and they look in the compartment under the drawer I’d be an asshole if I then also asked for a roll. Just charge them some “torch-burning time” instead. It’s OK that dice are used mostly for combat and for rolling random encounters and it’s OK if the dice are never touched for the entire session, it’s good, even. The dice & combat rules are like weapons on the table — you can have a very pleasant time without them, but when you have to use them, you want them to work well.
Speaking of time, letting time pass is one of the hardest things to do as a new DM. You’re in charge of letting time pass, of letting the sun move in the sky, of letting the torches burn down. Time passes as just as quickly or as slowly as it needs to do to answer the question at hand. Charge food, charge torches, make encounter checks, move on. Some players that are uncomfortable with “losing sight” of their characters by “camera cuts” are OK with a fast forward.
DM: “OK, so after three days of this — scratch three days of rations,
by the way —”
Player: “Hold on, I want to forage/craft during that time”
DM: “That’s OK. What did you want to do?”
This is a great exchange. If the players are doing things, let them. Just charge torch time. The players are in charge of the pacing, you’re just there to answer questions, but when you notice that their character are just waiting, let time move quickly.
Don’t think that if nothing happens during a few hours on planet Oerth that nothing should happen at the game table in that time. Time does not map 1:1 between the two worlds. Just immediately forward it ahead to when something does happen. This is the key to make the game full of action without a bunch of prepped action “scenes”. A long voyage at sea with like only 15% chance of something happening every day? Then don’t play out every day in excruciating detail. “You wake up as the sun rises over the eastern horizon, making the sea glitter, the seagulls are, as always… etc etc etc”. Just make the rolls for the days until something happens.
Details are great the first time something happens while chores and repetition are boring. The first time they set up camp it can be great to see: do they make a fire? How are their tents placed? And so on. But the “we do it the usual way” is a fantastic way to answer those questions once they’ve set up a routine. So get into the mindset of curiosity: what questions do you need to have answered in order to move on?
That’ll help you both with time and with what level of detail is appropriate. “How do you open the door more specifically, do you touch the door handle with your bare hands, or what?” can be a fantastic question to ask once, even on an untrapped door, so you’re ready when there is a trapped door. “He looks at your sword with trepidation as he serves your ale” can be a great detail to give since it answers how adventurers are being looked at in a particular town. Questions you ask, and details you give, and the speed of which time moves, all serve the singular purpose of giving the group (including yourself) the answers they need to move on, no less, no more.