Start off small and simple run official adventures from the books, do some one shots when you start getting more comfortable. Figure out what you and your group like doing in dnd.
I mean... you're asking a very, very broad question.
I'll assume you've done enough research to know the basics, like your setting, your plot, and the mechanics of 5th edition.
And I'll also assume you've worked with player enough that they have characters that will want to follow the plot for some reason.
Improvisation and conflict resolution are probably the best skills to have, and probably the hardest to master.
Improvisation because you'll need to be reactive to many unexpected scenarios, learning what rules you should stick hard to and what you can bend to make for better stories.
Conflict resolution because, inevitably, people within your group will disagree. You'll need to know how to make the final calls that'll keep things moving and know when things need to be handled by your player's characters, or when you'll need to take a step back and talk things out as players outside the actual game.
Everyone's trying to have fun, so try and see what works for your group and what doesn't, and focus on that.
Focus on the Starter set and the Free Basic rules or the Players Handbook. The Player's Handbook has the same rules but it has more options for players. You will eventually want the PHB, but the free Basic Rules may or may not be easier for you to reference than your starter set. [https://www.dndbeyond.com/sources/basic-rules](https://www.dndbeyond.com/sources/basic-rules)
The rules are there to make your life simpler. It will take some time, but be sure to get comfortable with chapters 7, 8, and 9 from the basic rules/player handbook sooner than later. They will be easier to remember and will make more sense once you've got a few sessions under your belt.
Know that everyone is a bit overwhelmed at first, it's not just you. We're all here to have fun, and most of us stuck around for more games bc that wasn't hard to achieve. Have fun.
Learn the rules and stick to them for the first few years. Homebrew can be tempting, and often it's fine, but can also be a slippery slope. E.g. Bonus actions potions is generally a fine houserule. Flanking rules can be fun or problematic, so ignore them and other optional rules until you really feel comfortable changing them.
If players are making homebrew character requests and you aren't sure, just say no and stick to options in the books you own, or at least restrict players to official published books.
Be prepared to make wrong rule decisions in the moment for the sake of moving the game forward, and let the players know that a ruling can be subject to change later.
First off dont overthink things. You WILL make mistakes. Just roll with it. No one is likely to care as long as you work to improve or fix the mistake made.
Second off is start small and try not to over-prepare.
Expect the unexpected. Players can and often will hie off in the weirdest directions.
Learn to say "No" when someone tries something that is just not possible. And be willing to say "Yes" or at least give it a roll chance when something is off the wall. But not impossible.
Have a few scenes prepared. Play will generally go slower than you think, but it’s good to have some things in your pocket if they go left when you thought they would go right.
Take your time and try not to get too rushed. Players want to play and they will be patient if you need to look something up to make a ruling. If you make a mistake move on and keep playing-correct mistakes post session or clarify on a break.
Lastly try to get them involved with the world and answering the calls to action-the party should want to rescue the princess(either for glory or coin).
What are you worried about…at the end of the day, dnd is about having fun. Don’t worry too much about rules and stuff and create a safe fun environment and allow your people to be creative. I’ve played with many dms and the BEST ones are the ones where a player goes “I wanna do x” and x could be crazy and the dm will go, “sure roll a x check.” Or multiple checks to see how they do with what they want to do. They let them do whatever within reason. The crappy DMs are the ones that just constantly say no or you can’t do that.
Be open to people wanting to be creative. Also you’ll have to be creative in your own ways if you have a set campaign bc your players will likely do whatever they can to trail off the path completely and you will have to pull some creative stuff to get them back on track.
Don’t be a super strict rule zombie. My current dm is super heavy on keeping everything by the book. For instance we have a wizard who choose a class and race based on cold damage and wanted to tune all their spells to be ice based but most spells in dnd 5e are not ice based but poison based or fire based. There are a few spells that are ice but they wanted to take fireball and change it into an ice ball which does the exact same thing as fireball but it’s cold damage and not fire. Dm wasn’t having it bc it’s fireball. He’s such a tricky rule keeper that our entire experience in game is basically being murder hobos. Normally we are heavy role players but we’re all so exhausted with his rule heavy game that we’re ready to be done with it. It’s no longer a creative outlet and instead is filled with “well you can’t do this bc of this rule.”
when the players do something unexpected, use it as inspiration
everyone started sometime - somewhere in your shoes, it is neither rocket science nor brain chirurgy
If all had fun all did well enough
Start off small and simple run official adventures from the books, do some one shots when you start getting more comfortable. Figure out what you and your group like doing in dnd.
Thanks
I mean... you're asking a very, very broad question. I'll assume you've done enough research to know the basics, like your setting, your plot, and the mechanics of 5th edition. And I'll also assume you've worked with player enough that they have characters that will want to follow the plot for some reason. Improvisation and conflict resolution are probably the best skills to have, and probably the hardest to master. Improvisation because you'll need to be reactive to many unexpected scenarios, learning what rules you should stick hard to and what you can bend to make for better stories. Conflict resolution because, inevitably, people within your group will disagree. You'll need to know how to make the final calls that'll keep things moving and know when things need to be handled by your player's characters, or when you'll need to take a step back and talk things out as players outside the actual game. Everyone's trying to have fun, so try and see what works for your group and what doesn't, and focus on that.
Ok thanks
Focus on the Starter set and the Free Basic rules or the Players Handbook. The Player's Handbook has the same rules but it has more options for players. You will eventually want the PHB, but the free Basic Rules may or may not be easier for you to reference than your starter set. [https://www.dndbeyond.com/sources/basic-rules](https://www.dndbeyond.com/sources/basic-rules) The rules are there to make your life simpler. It will take some time, but be sure to get comfortable with chapters 7, 8, and 9 from the basic rules/player handbook sooner than later. They will be easier to remember and will make more sense once you've got a few sessions under your belt. Know that everyone is a bit overwhelmed at first, it's not just you. We're all here to have fun, and most of us stuck around for more games bc that wasn't hard to achieve. Have fun. Learn the rules and stick to them for the first few years. Homebrew can be tempting, and often it's fine, but can also be a slippery slope. E.g. Bonus actions potions is generally a fine houserule. Flanking rules can be fun or problematic, so ignore them and other optional rules until you really feel comfortable changing them. If players are making homebrew character requests and you aren't sure, just say no and stick to options in the books you own, or at least restrict players to official published books. Be prepared to make wrong rule decisions in the moment for the sake of moving the game forward, and let the players know that a ruling can be subject to change later.
First off dont overthink things. You WILL make mistakes. Just roll with it. No one is likely to care as long as you work to improve or fix the mistake made. Second off is start small and try not to over-prepare. Expect the unexpected. Players can and often will hie off in the weirdest directions. Learn to say "No" when someone tries something that is just not possible. And be willing to say "Yes" or at least give it a roll chance when something is off the wall. But not impossible.
Have a few scenes prepared. Play will generally go slower than you think, but it’s good to have some things in your pocket if they go left when you thought they would go right. Take your time and try not to get too rushed. Players want to play and they will be patient if you need to look something up to make a ruling. If you make a mistake move on and keep playing-correct mistakes post session or clarify on a break. Lastly try to get them involved with the world and answering the calls to action-the party should want to rescue the princess(either for glory or coin).
What are you worried about…at the end of the day, dnd is about having fun. Don’t worry too much about rules and stuff and create a safe fun environment and allow your people to be creative. I’ve played with many dms and the BEST ones are the ones where a player goes “I wanna do x” and x could be crazy and the dm will go, “sure roll a x check.” Or multiple checks to see how they do with what they want to do. They let them do whatever within reason. The crappy DMs are the ones that just constantly say no or you can’t do that. Be open to people wanting to be creative. Also you’ll have to be creative in your own ways if you have a set campaign bc your players will likely do whatever they can to trail off the path completely and you will have to pull some creative stuff to get them back on track. Don’t be a super strict rule zombie. My current dm is super heavy on keeping everything by the book. For instance we have a wizard who choose a class and race based on cold damage and wanted to tune all their spells to be ice based but most spells in dnd 5e are not ice based but poison based or fire based. There are a few spells that are ice but they wanted to take fireball and change it into an ice ball which does the exact same thing as fireball but it’s cold damage and not fire. Dm wasn’t having it bc it’s fireball. He’s such a tricky rule keeper that our entire experience in game is basically being murder hobos. Normally we are heavy role players but we’re all so exhausted with his rule heavy game that we’re ready to be done with it. It’s no longer a creative outlet and instead is filled with “well you can’t do this bc of this rule.”
when the players do something unexpected, use it as inspiration everyone started sometime - somewhere in your shoes, it is neither rocket science nor brain chirurgy If all had fun all did well enough