1. Find Some Players - This part is important. Even though you can start without any players, you will need some eventually. Don’t go too big - no more than 15. You can go as small as one. remember, your players are your friends and they want to have fun.
2. Session 0 - Talk to your players and find out what kind of game everyone wants to play. Maybe they want a silly game or an ultra-serious game with lots of vampires. Maybe one person hates undead children and doesn’t want you to use them. This is a great time to discuss house rules and your vision of the game. You can also discuss snacks.
3. Start Small - You don’t have to build an entire world and create all the gods and their history to run a game. Come up with a place the game will start. Maybe it is a small town or a crossroads in the forest or a tavern in a city. Create some fun details about the place. Since this is where things start, make it good.
4. Create Fun NPCs - Think about who is around when the game starts. The half-orc bartender who used to be an adventurer. The old mayor who everyone loves. The young lady who sees ghosts everywhere. The weird warlock who no one likes. The bard who tells funny stories. These are the first people your players will meet in your game so make sure they are fun.
5. Create a “Bad Guy” - It doesn’t have to be a person. It can be a group of goblins or a curse or a forest fire. Someone or something that creates danger or problems. It helps if the danger is serious so the characters are motivated to take care of it. This needs to be something the characters can defeat in the first session so they feel important.
6. Figure Out Who is Important - Come up with three people who are essential to defeating the “bad guy.” A beggar has seen some things… a knight fought the bad guy and lost… a scout knows the way… a witch knows the cure… a noble has a secret… a woman is really evil…
7. Make a Map - This isn’t required but it is fun and can help. Make a tiny dungeon with a few rooms and secret doors. Map a town or village with several landmarks. Make a regional map so the characters know where they are going. Don’t pretend you can’t draw… I am only 6.
8. Treasure - Defeating evil is its own reward but treasure is more fun. Give them gold and gems only if you want Session 2 to be a shopping episode. Instead, give them something magical that they will have fun using. Knowing the characters' desires and abilities can help when you pick out treasure.
9. Level-Up - If the characters started at level one, you can easily level them up after they defeat the bad guy. It makes things more fun and exciting for the players and they will think you are an awesome DM. Plus you can then make the next bad guy even tougher.
10. What’s Next? - After the session, talk to your players and see if they had fun. Ask for feedback. Then start planning Session 2. You can turn one of the NPCs from Session 1 into the new bad guy or move the story in a different direction. Have fun and good luck!