|reach in and pull out a tip! i promise it won't bite, i've trained it well|
art by Miranda Sider
2. Or better yet, let your players do the building. Some players love reading expansive loredocs, making/reading wikis, looking upon your face adoringly as you expound on the minutia of your setting. Most don't care and won't read the 2-page setting doc you send out or hand them at the table. Giving some creative control to the players lets them have some buy-in, gives them a little customization for their characters' cultures and personalities (especially in systems where they'd be rolling mostly-random characters), and gives them something to care about. I like making my players' characters foreigners and letting the players make up where they're from; it saves me tons of setting work and means that I can reveal the setting of the game proper through play rather than giving a big exposition talk beforehand.
3. Talk with your players before the game starts, whether that's for five to ten minutes before the con game starts, or in the group chat where you've assembled your players to schedule games. Get everyone on the same page regarding table expectations, game themes, character death, system options, PvP combat, railroads, etc - and especially content warnings and topics that are unwelcome at the table. So many RPG horror stories have come from players not knowing what's okay to talk about at the table - and while a lot of it should seem like common sense, common sense isn't common, and it's way easier to shut problem players down when you've established guidelines for behaviour beforehand.
4. Rule of Cool. The answer to "is this cool thing in the scene so I can do something cool" is almost always yes. "Is the duke having a meal so I can try to slip poison into his food?" "Does the castle wall have arrow slits I can peek and shoot through?" "Is there a chandelier in the hall that I can detonate and cause mayhem at the ball?" Unless it's patently ridiculous or you've already established something to the contrary, imho, you should let them go for it. When you make rulings (because you're making rulings, not looking up rules - one of my favorite OSR paradigms), err on the side of making players feel good. That doesn't have to mean that they succeed, but it does mean that interesting things happen. Sometimes the coolest thing that can happen is character death. This does mean you have to be on the same page as your players, and understand what they want out of the game, but you should have talked about that already (see prior tip).
5. Chekov's guns are a sometimes food. If it's not going to be mechanically or interaction-relevant, don't put much emphasis on it - and when you do emphasize something, let the players use it. This is mostly regarding setting and plot info - if there's twelve noble houses and only two are relevant in the next few sessions, leave the other ten out of your description to the players, even if you've built them ahead of time. If the players want to ask, then give them the loredump - but too much information just causes decision paralysis and drags them away from whatever you've prepped. On the other hand, if you describe a granary tower in the bandit camp, let the players blow it up to cause a distraction; don't force them through fighting twenty bandits.
6. Handwave things. You do not, cannot, and should not, try to explain everything away in lore-friendly ways, because that does not work. I have spent literal days of my life arguing with other GMs about where to put teleportation circles in settings so that characters can move between parties if their players want to try a different GM for a week. I have seen dozens of stories online about how a GM took control of an absent player's character, or gave the character to another player, and killed the character while the player was absent. If a player is absent, just let the character not exist for a bit, don't explain it, don't justify it. Verisimilitude is valuable, but when you try to explain real-world phenomena with in-game logic, you're just making it harder on yourself.
7. Don't try to fix out-of-game problems with in-game solutions. Talk to your players. Make your expectations for their behavior clear. If two players have beef with each other, or someone has issues with you, speak with them about it outside of the construct of the fiction. You're all there to have fun, so if someone isn't having fun - or if someone's idea of fun is making the game unfun for others - something is going wrong. Ask the players who are having problems what's up, and mutually figure out a solution that works for all parties involved, without the pretense of verisimilitude or the rules of the game getting in the way. Also, consider if you might be the problem; not all players are up for all games, and if they're not having fun because of the game you want to run, you either need to run a different game or find players who're up for what you're running.
8. Put your characters somewhere they're going to be doing interesting things. Too many settings I've seen (currently my big pet peeve is Lancer) have so many cool ideas, and all of them are secrets to virtually any PC that'd be created, and wouldn't be revealed until well into a campaign. If there's fun stuff you want players to interact with, give them a chance to do so when the game starts, even if they don't grasp the full scope of the conspiracy, or explore the depths of all the multifarious demiplanes, or whathaveyou. Put cool stuff everywhere, and don't worry about "balance" or "level-appropriate rewards/enemies/phenomena". If you want your players to explore the City of Brass and make enemies with the djinn, don't save that for level 7 when you're starting the game at level 1 - put them in the City at the start, because at worst, even if the campaign collapses early, you've gotten a chance to play with the cool stuff too.
9. Encourage bad decisions. It's in the tagline of Mimics & Miscreants for a reason, and I wholeheartedly believe that making bold, risky, bad decisions is the heart of how I enjoy RPGs. Payoffs are all the sweeter when you've risked everything to get there, and surviving a dungeon has meaning when some characters didn't make it out. Note that that doesn't mean make every test a one-in-a-hundred miracle to pull off - that discourages bad decisions; too much risk will only make players want to do everything the safe and boring way. Instead, let players get themselves into hot water by taking actions that'll definitely work, and definitely have bad consequences, but might (might!) work out in the end if they're smart and play their metaphorical cards right.
10. Accept that your game will probably end prematurely. There's few things more disheartening than a campaign petering out because of scheduling conflicts, players getting bored, or the GM getting bored - but I've been in very few campaigns that've ended with a bang rather than a whimper. This doesn't mean the game is a failure! It just means that you need to plan shorter-term, and ensure that there's good content from start to finish, so that everyone comes away feeling like they've accomplished something even if the campaign never makes it past session 3 or 4.