Hi, firstly if this is your first time GMing grats on taking the GM/DM chair!
My general tips are…
1. Index Cards/Note Cards can save you a lot of time! I keep stats for each monster I am going to use as well as variants, NPC information, boxed text and item descriptions.
2. Keep a list of names handy divided by race, some for inns/taverns and ships can be handy too.
3. Listen to your players when they express opinions on NPCs, quests, villains etc they will often express ideas that you may like better than your own.
4. Have players make their characters together, they are more likely to play off elements of each other’s back story and build a cohesive group.
5. Don’t bog the game down with too many random encounters. I try to limit them to once per leg of travel and if taking a long rest in a dangerous place. The rest are planned encounters (some of which my players think are random). Not all of my random encounters are combat related either, weather, traders, magical phenomena, other travelers, omens etc work just as well.
6. Don’t over prepare, you will end up wasting time on things you don’t need.
7. Establish any basic rule changes during character creation. There’s less likely to be complaints or hurt feelings if you establish things early on. Some people houserule Intimidation so that it can be used with Strength or Charisma, a Barbarian or fighter will likely want to know thins when allocating stats.
8. Be up front about the kind of game you’re running. Do you allow PVP, is it all hack and slash dungeon crawls, will there be lots of political intrigue, evil?
You can also check previous posts tagged:
Beginner Tips
GM Tips
DM Tips
Player Tips
New Player Tips
Here are Matthew Mercer’s GM Tips HERE or HERE
Matt Colville’s running the game playlist is great too!
If you are playing D&D and have any new players show them These How to Play D&D videos