Collected below are little nuggets of good advice for gamemastery we've come across.
Keep these in the back of your mind as you embark on your adventures.
Railroading is when you require specific outcomes to happen and start negating player agency to make things go your way. Don't instruct players where to go, or use NPCs to tell them what to do. If they manage to bypass something you set up cleverly, don't invent new problems for them that negate their success because you don't know how to react to their ingenuity.
LIE ABOUT CHOICE
You're not roleplaying if the players can't make meaningful choices in the game. If you create multiple fake "options" that all lead to the same outcome, that's just a hidden railroad that negates player agency.
Fudge Dice Rolls
Fudging dice rolls is cheating, plain and simple. When you fudge, you're playing by different rules than the table agreed upon. It deprives players of meaningful choice and it destroys the trust players put in you to be an impartial referee at the table. If you do it to save PCs or NPCs from harm, then you're deflating tension; if you do it to pre-determine outcomes, then you're railroading. Fudging dice rolls is never an acceptable practice in OSR+.
SAY THE WORD IMPOSSIBLE
If some action is not outright forbidden by the mechanics, then it's possible to try it. But that doesn't mean it's probable. Even the most unlikely things are possible: "I'd like to teleport into the Astral Veil" is possible, it just requires insanely powerful magic that the PC may not have at their disposal. Similarly, if the player wants to dispel evil from a curse placed by literal Satan onto a pentagram, you could still give them a chance to try by setting a legendary TN of 25. Instead of saying "That's impossible," always ask, "How do you do it?"
Tell PCs What They Think
The only thing players have complete control over in the game are their PCs. While you can tell players how their PCs might involuntarily feel ("You feel cold; a sudden vision comes upon you"), how they interpret that feeling and react to it is up to them.
Don't be afraid to act like a carnival barker when you need to. Constantly rotate the spotlight across the table, giving everyone an opportunity to say what they want to do (even outside of initiative). Don't delay the resolution of actions unless another player or NPC can intervene, or something hidden you are introducing to the scene does. And if you do defer resolution in order to collect everyone else's intentions, make sure to resolve things in the order they were collected so that the first player to say what they want to do isn't stuck waiting at the end of the resolution queue.
Tension and conflict are enhanced by urgency. If the players have all the time in the world to do something, then there's nothing at stake. Liberally introduce clocks to create deadlines and prevent them from frequently resting and gathering resources. Entice them into immediate action with rewards. Push them forward by triggering floating scenes.
Be a Fan of the PCs
In addition to being a neutral arbiter of the rules, you're a player in the fiction who wants the heroes to succeed. "Winning" in OSR+ means everyone at the table gets a chance to resolve their PCs' conflicts, even if that means the PCs fail. But in order for that experience to be enjoyable, play needs to be challenging, and something needs to be at stake. Being a fan of your PCs means giving them an opportunity to earn that success, and cheering them on when they try to pull it off.
While you don't want to railroad your players, you sometimes have to herd them like cats to keep them engaged with the adventure. Be permissive with information that can be gleaned from their interrogating the lore or investigating the scene so they can decide where to go next. Ask them "What do you do?" and "What's happening now?" when there's a lull in the decisionmaking, and be generous about reminding them about the information they've discovered, so they can make informed choices.