For a beginner campaign, it’s best to go with something fairly open and flexible, then add more specific details to suit the characters your players are making. A classic first world-building project is to create a town on the frontiers of civilization – a place that can act as a safe haven and ‘hub’ for your adventuring party, from which they can explore outward into the wilderness.
With these basics in mind, talk to your players about the characters they’re going to make, so you can include relevant locations in your world.If you’ve got a Rogue in the party, perhaps include a thieves guild for them to work with. Adding these kinds of character-specific locations will help your players actively engage with your world, rather than treating it as a backdrop for adventuring.
Now that we know what we need to create a TRPG world, let’s go about actually creating it. You might find coming up with locations and people to be tricky, but there are plenty of online resources you can use to speed up the process.
Just remember to ALWAYS say your names out loud to check how they sound before you use them in your game. You don’t want to base your campaign in the town of ‘Diznauts’ and spend half an hour trying to get your players to stop laughing at you.
With names selected, you might want to map out your town. Drawing it up with a pencil and paper can be fun, but if you want to make a digital map (and you’re willing to pay a little money to do so), I’ve found great success with Wonderdraft and Inkarnatem.
Both will take some practice, but the results are more than worth it.
If you’re having trouble with ideas, you could also try the excellent town generator by Watabou. Just remember, while maps are fun to make and use, they’re absolutely non-essential for a TRPG experience.
Finally, the best resource at your disposal is every piece of media you’ve ever consumed.
When it comes to making a world for your own personal use, don’t hesitate to steal inspiration from everywhere you can. For the best results, use ideas from media that your friends haven’t seen before (this will make you seem more original, a great boon for any DM).