Once you have a group together you have to actually run some games. Having done this I thought I would share some of my lessons learned.
Organization - Nothing slows down the game more than when the DM can't find his notes or has to flip through a rulebook. There are times when I think it's OK to look up a rule, mainly when it's a new game and you want to get it right early to make sure everyone understands the fundamentals. Most of the time though it's better to make a ruling, roll a die, and move on.
- Games with universal mechanics make this easier to do as you likely know how the core mechanic works already.
- I've posted about campaign binders before and since that's how I do it I only have one pile of paper to bring to the table. At most I have to flip through a binder, I don't have to search the entire house.
- Opposition Stats - For 3E I printed out about 200 index cards with monster statblocks on them, kept them in a cardfile with alphabetical dividers, and almost never touched my monster manual again. It's easier to manipulate a couple of cards behind the screen than it is to keep a monster manual open and accessible. I did the same thing for d20 Star Wars when I ran it (they were handwritten that time) and I am doing it again for Saga as in those games certain opponents come up repeatedly - Stormtroopers, AT-AT's, Tie Fighters - so it makes sense to have standard stat blocks for them at hand during every session. For the 4E D&D game I use an image program to cut the relevant monster statblocks out from the Monster Manual PDF's, paste them all to one sheet , then print it out and add it to my material for that session. Each of these lets me reference "Monster X" in my notes and access those stats easily without having to pull a book out.
- Combat Order - You can't run an efficient game if you have to constantly ask who's turn it is. For D&D and other "Roll Initiative" type games I put each character down on an index card (name,class, whatever) and when combat breaks out I make one for each monster group as well. Everyone rolls initiative and I write it down on each card then put them in order. Then I cycle through the deck each round. This is better than the write-em down method as people sometimes change order during a combat and with cards it's as simple as moving the card to wherever it needs to go. I do not use player or monster stat cards for this as you usually need those stats when it isn't their turn, meaning you have to pull their card out of the deck and will probably get it out of order. It's just a way to track initiative, it's not a backup character sheet. That said I do note down conditions on them in 4E as it's a good way to remember saves and "turn ends" effects.
For Non-D&D games I use different approaches. For Shadowrun I wrote it on paper and then marked off as people took their actions. For Hero I used a copy of the Speed Chart in a sheet protector and marked segments off with wet erase markers. For Savage Worlds you use playing cards so you don't need a separate tracking method.
- Page Markers - If there's a page or two in a book that you will be referring to a lot then MARK THEM! I've seen DMs look up the same page multiple times during a session and have trouble doing it repeatedly! Just put a bookmark or a spare card or better yet put a sticky note or tab on that page so that it doesn't fall out. The XP tables in the DM's guide for 3E and 4E, sample NPC pages, the start of the treasure tables all have this in my library. In the PHB it's the level advancement page. It's the stuff you use all the time - make it easy on yourself.
- New players or inexperienced players will often fall into analysis paralysis and be unable to decide what they want to do. For these kinds of groups I like to have two different options planned out and then feed the group rumors, NPC requests for aid, talk of rewards for bandit heads - several obvious cues for the players to bite on. Don't worry about railroading these players - they need some help getting started, so give it to them.
- Experienced players will often come to the table with an idea of what they want to do already, either short term or long term or both. It might be "make it to level 2" or it might be "take over the world." Go ahead and focus on that process. It's not railroading if the players are demanding it. Find out in advance if possible and focus your prep there.
- Published adventures - these are both a curse and a blessing. They can be a blessing in that you don't need to come up with maps and badguy stats of your own, but they can be a curse when the map and the descriptions don't match up, or when the NPC's don't make sense because something is missing or when you cannot wrap your head around the plot described in the adventure and you waste a bunch of time trying to figure it out. I've brought several sessions to a crashing halt using published adventures when I am running one and suddenly realize I don't know how dungeon level 1 connects to dungeon level 2 either because of an unclear map, an editorial mistake that trimmed it out, or my own reading comprehension error.
- Self-Made adventures - one way to guarantee that you know how one level connects to the next or to know for sure why Doctor Kaboom is robbing Novatech Labs this week is to write it yourself. It's more work up front, sure, but you never have to try and figure out what the author intended. Plus they are typically re-usable even in different games. A good idea is a good idea.
- World building - this was good advice in The Dragon in the late 70's and it's good advice now so I will repeat it: The Bullseye Approach. Work up a rough sketch of a town. Work up a dungeon outside of or underneath that town. Bam! You're ready for your first session. Now work up some of the countryside around the town. Work up a few NPC's. Work up a few organizations that are important to the area - temples, merchants, bandits, orc tribes. make up some names of other places in the region. What kingdom are we in? What kingdom is next to that? Keep going like this, coming up with stuff as it's needed rather than trying to create a entire detailed world from scratch in advance - because much of it will never be seen by your players and is a waste if you have really limited time to prep. Focus on the parts you will use and that your players will want to see, not the family tree for the ruling clan of the island nation that no one is from and no one plans to visit - that's not game prep that's stuff you're doing strictly for yourself. The town might be several pages worth of information. The nearby forest and lake and hilly region might get a paragraph apiece. Neighboring kingdoms might get a sentence. Distant kingdoms might be just a name. As your players explore, you fill in more details, which has the added benefit of letting you use your players ideas. "Wouldn't it be cool if there was a kingdom run by hobgoblins around here?" lets you take the Kingdom of Harktor, which was just a name up until that session,and decide it's a feudal society of hobgoblins. Prod the players for more info - what would be cool about that? Would they be enemies or allies? What would they be know for? It's bound to go somewhere interesting, so use it.
For examples of this in action, check out the material on Shadowdale in the Realms or the City of Greyhawk in Greyhawk where there are tons of detail on the local region and the more distant stuff tends to be general sketches instead of specifics.
Also take a look at the early episodes of Original Trek - the uniforms change all the time, the ship's capabilities vary somewhat, personalities shift, and the structure of the organization they work for is very fluid - it's not even called Starfleet for some time. Despite the huge volume of canon out there now they didn't know all that stuff ahead of time - they made it up as they went along.
- Having a pile of pre-generated short adventures and NPC's and even maps is a godsend when you are winging it, and at some point you will need to wing it/ For 4E Dungeon Delve is a wonderful resource. For 1E and 2E it was the Book of Lairs. For Superhero games it's those books of Supervillains like Marvel universe, Enemies, Crooks, etc. Maps are tougher but published adventures are a good resource here too. Building up these resources takes time but is well worth it when the time comes.
- Practical stuff: Have a set place to play. Set your table up before everyone gets here. Put a cloth over it or something to let everyone know that it's game time. Have your books out. Have the miniatures out. Have your dice out. Have your screen up - all of these little cues let everyone know that you are ready to go and that you didn't forget about the game until someone knocked on the door. I don't manage this every time but I do try to look like I'm ready to go when people show up most of the time
- We stop at midnight.If we're very close to finishing something or hitting an important milestone then I will push a little bit past it but I err on the side of "stop early" rather than "stop late" as some people work the next morning and have to get to bed and others worked all day and are nodding off if we play longer. This also gives everyone an incentive to stay focused as we're stopping at 12 whether you wasted an hour talking about comic books or Clone Wars or not.
- If someone is away from the table when their turn comes up in combat then we skip them and let them jump back in when they return. We don't change up the initiative order, we just have a 1-round "wrinkle in time"
- We never end in the middle of combat, period. It's too hard to recreate the exact scenario a week or two down the road and I can't leave stuff out and undisturbed for that length of time. Sometimes this means we wrap at 11:30 but the group has decided that this is a better approach than running long. At most I will set the scene as in "you walk into the room and 15 skeletons rise up out of the mud. We will roll initiative next week."
- Most of the time I use a battlemat with overhead markers. If I have a preprinted map that fits the scenario, I use it. If I have time and think it will be reused I will draw out a map on a page of presentation graph pad paper, one of those big ones you can get at office depot. If I have the right tiles I will use dungeon or galaxy tiles. Even if it's not a tactically-focused game like D&D, I still like to have a map of some kind on the table so that players can see relative positions. "OK Aluminum Man is on top of the Chrysler Building while Oonga the Fire-Ape comes down Broadway and Captain Vesuvius comes ashore near Battery Park."