>>223817
>World Building
The best advice I can give you is to start out with a few key elements like what you do and don't want, and then randomize it from there. Not bat shit crazy but once you establish some basic world lore, mistakes can usually be sorted out logically from there. Examples of things like fighting machine people, mean you can find otherworldly devices or if fighting ancient evils, you could end up fighting unspeakable horrors of a distant star.
>Creating a Plot
This relies on your players and your vision. As a DM you are there to help the players create and tell a story. You are the obstacles, the plot and the rewards they seek, so when creating a plot don't be afraid to cater to them on occasion when they aren't fighting The Ancient Evil. This doesn't mean, let them walk all over your plot with their childish bullshit, you are the DM. In my case, I call myself the Story Teller and while the players can be friends or family or people you care about, if you just let them twiddle their thumbs, tripping over bags of unnecessary loot, it won't matter much.
If you want to start small go with the formula of "X does Y because Z" or "W does X because Y does Z". you can move that out however, but making easy plots and hard plots are, to me, decided by how many ways you can solve the problem.
A good story has a neatly wrapped up little ending. A great story has many ways to do this.
>Inter-party conflict
This is a combined cause of your own moral guidelines and sometimes the players standing together on something. In most cases I've experienced "Sort this out when there isn't a body count" works long enough for them to work together. Then after that, discuss things. Don't be a weasel about it, if they're your friends, your real friends, they'll see their errors. If not, then you have just gained some insight.
I've had everything from repeated rape to the burning of entire civilizations happen at my table and it's not about whether it's happening, it's why they're doing it and does it make sense.
>Utilizing NPCs
First thing I will always tell you about making an NPC? Use part of who you are. Not some Mary Sue invincible bullshit, ego-driven garbage. Make characters from moments of your life. Then stat them. What do they represent or do? When utilizing an NPC the best thing I can tell you is that while every NPC you make to Mean something, all rectangles are squares. Sometimes you have to dress up or put on a voice or try really hard, but at the end of the day you can place them to a T in what they are. And this does not mean that you make a "brooding anti hero with 18 Dex and 14 blah blah blah was based off of the pain of my dying grandma" and use it like that means something. Because easy tip, unless you convey the emotions or their meaning to your party, any NPC is any NPC. Every Rectangle is a Square.
>Dealing with Combat
Well Kid, all I can tell you is know the basics well enough. Some fights are easy, some are tough but when you're talking about flow? Try to keep the enemies going as one unit, not a bunch of separate entities.
Don't force high-level random shit unless people go looking for it. But also don't afraid to pull off a "You find a lone Orc standing in a field", and what that means, is divert their expectations. They expect it to be a pushover? Give them a wholloping. Don't be cruel, as they are your players, but don't let them estimate you.
>Is Music a good idea?
Almost 90% of the time you can make an almost basic experience better with music. I use soundbytes sometimes myself, from radar blips to air raid sirens. You use music to convey a tone. You want creepy? Look for the score to the Shining or Silent hill.
Emotional? Sometimes Visual Novels or adventure games like Skies of Arcadia.
But I prefer basic ambiance. Water dripping in caves, wind blowing. Stuff like that.
>Props
It depends on the scenario. I have used Chick Filet cups with incense stubs stuck out of it to be hangman's gallows around a tower. You have to focus on two things; How hard you can sell the idea of something, and how hard your players can buy into it. If they believe in the way something looks is good enough? It will work.
>Dungeons
I don't run actual DUNGEONS very often but when I do I make it a development. I don't see them as these places of sprawling wonder and great joy. Often they are desolate, isolated and cold. Places where you can gain loot, but if something was actually living here, it'd be obvious. After all, if a horde of goblins live in a cave, they got to shit right? And if they don't eat it (or do) the smell will be awful.
Dungeons can be combat wonderlands, but I prefer tight, dark places to be team-building exercises or think tank sessions.
That's what I can give you. I probably triggered a few people by not being a merciless asshole to my players but eh.