1. Recruit your players
There are two types of friends you need to recruit when putting together a party.
A) The nerdier friends who are SUPER EXCITED to play and have already written a four-page background story on their character.
B) The... less nerdy friends, who at first don't fully understand what is happening.
2. Set a date!
Find a date that works, and then another one, and then another one. Keep scheduling dates until people stop cancelling or making excuses because of work. You'll need a whole evening to properly get into things, and unless you go with a short 'one-shot' adventure, you'll need to arrange several dates to finish a whole campaign.
3. Learn the rules
You poor fool. You really thought this would be easy didn't you? If you're the unlucky member of your friend group who got stuck with the job of Dungeon Master then you've got your work cut out for you. The world of Dungeons & Dragons is vast and complex. Sure, the BASIC rules are easy enough to grasp once you take the time to read them, but you have to be over-prepared to handle your PLAYERS, who are likely to try and break the game at any given opportunity.
4. Help your players create their characters
The first step to helping your players understand the rules is by creating their characters. The nerdier players have had theirs ready for weeks, but this is the first opportunity to get the more skeptical players excited!
5. Exercise patience
What's super important for a new Dungeon Master to remember is that the players may take time to grasp the game fully. Let them explore. Allow them freedom to follow their quest at their own pace and don't box them in to a single narrative too rigidly.
6. Nudge the players in the right direction if they need help
The players may get stuck, or even go in entirely the wrong direction. The role of the Dungeon Master is to give them a slight nudge in the right direction. This requires SUBTLETY. You want the players to feel like they're making the decision for themselves.
7. Finish every session with a satisfying cliffhanger
You want to entice your players to play again? There's noo better way than to leave things open-ended. The World of Dungeons and Dragons is limited only by your imagination, and the adventure can always continue!